Self-assembling magnetic anastomosis device having an exoskeleton

ABSTRACT

The invention is an implantable magnetic anastomosis device having an exoskeleton that directs self-assembly. The design allows the device to be delivered in a linear configuration using a minimally-invasive technique, such as endoscopy or laparoscopy, whereupon the device self-assembles into, e.g., a polygon. A coupled set of polygons define a circumscribed tissue that can be perforated, or the tissue can be allowed to naturally necrose and perforate. The device can be used to create anastomoses in a variety of tissues, such as tissues found in the gastrointestinal, renal/urinary, and reproductive tracts. New procedures for using anastomoses, e.g., surgical bypass are also disclosed.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/522,977, filed Oct. 24, 2014 (now U.S. Pat. No. 9,763,664), which isa continuation of U.S. patent application Ser. No. 13/896,670, filed May17, 2013 (now U.S. Pat. No. 8,870,898), which claims priority to U.S.Patent Application No. 61/649,248, filed May 19, 2012. U.S. patentapplication Ser. No. 13/896,670 is additionally a continuation-in-partof U.S. patent application Ser. No. 12/984,803, filed Jan. 5, 2011 (nowU.S. Pat. No. 8,828,032), which claims priority to U.S. ProvisionalPatent Application No. 61/292,313, filed Jan. 5, 2010. The contents ofeach of the aforementioned applications are incorporated by referenceherein in their entireties.

FIELD OF THE INVENTION

The invention relates to surgical methods, apparatus and kits,especially minimally invasive endoscopic and laparoscopic techniques forcreating surgical bypass (“anastomosis”) using a magnetic compressiondevice. The invention also relates to medical applications for whichsuch a magnetic compression anastomosis device could be used.

BACKGROUND

Surgical bypass (anastomosis) of the gastroenterological (GI), vascular,or urological tracts are typically formed by cutting holes in the tractsat two locations and joining the holes with sutures or staples. Theprocedure is invasive, and subjects a patient to surgical risks such asbleeding, infection, pain, and adverse reaction to anesthesia.Additionally, an anastomosis created with sutures or staples can becomplicated by post-operative leaks and adhesions. Leaks may result ininfection or sepsis, while adhesions can result in complications such asbowel strangulation and obstruction. Additionally, while traditionalanastomosis procedures can be completed with an endoscope, laparoscope,or robot, it can be time consuming to join the holes in the tissues.

As an alternative to sutures or staples, surgeons can use mechanicalcouplings or magnets to create a compressive anastomosis betweentissues. Using surgical techniques, such as endoscopy or laparoscopy,couplings or magnets are placed over the tissues to be joined. Becauseof the strong compression, the tissue trapped between the couplings ormagnets is cut off from its blood supply. Under these conditions, thetissue becomes necrotic and degenerates, and at the same time, newtissue grows around points of compression, i.e., on the edges of thecoupling. When the coupling is removed, a healed anastomosis between thetwo tissues is formed.

Nonetheless, the difficulty of placing the magnets or couplings limitsthe locations that compressive anastomosis can be used. In most cases,the magnets or couplings have to be delivered as a completed assembly,requiring either an open surgical field or a bulky delivery device. Forexample, existing magnetic compression devices are limited to structuressmall enough to be deployed with a delivery conduit e.g., an endoscopicinstrument channel or laparoscopic port. When these smaller structuresare used, the formed anastomosis is small and suffers from short-termpatency, typically lasting several weeks at best.

To overcome the limitations of the mechanical or magnetic couplingdevices described above, researchers have developed deployable magneticanastomosis devices that can be delivered via a delivery conduit. Upondelivery, the devices are intended to self-assemble in useful shapes toform the anastomosis. Such devices are reported in U.S. Pat. No.8,118,821, incorporated by reference in its entirety. Unfortunately,these designs are not sufficiently robust to be adapted for human use.In some instances, the magnetic pieces become separated from theanastomosis device, creating a risk of blockage in unintended systems.In other instances, the anastomosis devices do not self-assemblecorrectly and require additional surgical procedures to remove themalformed device. Regardless, previous clinical trials have met withlittle success. See, e.g., U.S. NIH Clinical Trial NCT00487552,terminated for failure to meet a primary endpoint.

Thus, there still remains a clinical need for reliable devices andminimally-invasive procedures that facilitate compression anastomosisformation between tissues in the human body.

SUMMARY

The invention described herein overcomes the shortcomings of the priorart by incorporating an exoskeleton that directs self-assembly of themagnetic anastomotic device, thereby assuring that the deviceself-assembles properly, and that magnetic segments are not dislocatedor dislodged during deployment. In particular, the invention provides animplantable anastomosis device comprising a plurality of magneticsegments coupled together with an exoskeleton that directsself-assembly, e.g., made from a shape memory material, i.e., shapemetal, e.g., nitinol. The device can be delivered in a low-profile,linear configuration using e.g. endoscopy, or laparoscopy, or a needle.Upon delivery, the device self assembles to form a polygon, and can bepaired to a second polygon to join tissues, such as tissues of thegastrointestinal tract.

Using the devices of the invention, a wide variety of surgicalprocedures can be performed, including forming ports and anastomoses, aswell as connecting tissues with devices such as shunts. Typically, a setof two devices will be delivered to the tissues to be joined. Thedevices can be delivered either with the same device (e.g., endoscope)or different devices (e.g., endoscope and needle). The mated deviceswill circumscribe a portion of tissue that can be perforated (e.g., withcautery) for immediate access, or the tissues can be allowed to necroseover time and form an anastomosis.

Using the disclosed anastomosis devices (or other anastomosis devices ofsimilar functionality), it is possible to partially bypass bowel tissueso that only a pre-selected portion of the food and fluids traversingthe bowel travel through the anastomosis, while the partially bypassedbowel tissue continues to function in its native capacity. By using thistechnique, it is possible to predetermine a ratio of native to bypassednutrients, thereby allowing a surgeon to “dial in” an amount of bypassbased upon the desired endpoints. This functionality avoids manycomplications that arise with more radical (e.g., bariatric) surgery,such as extreme weight loss, bacterial infection and vitamin deficiencywhile providing an ability to control diseases, such as diabetes, thatpresent with a spectrum of conditions and severity.

The methods can be also used to treat diseases that require tissueremoval, tissue bypass, or fluid clearance. For example, the techniquescan be employed to treat cancers, gastrointestinal diseases, andcardiovascular diseases. Because the devices are relatively simple touse and can be deployed with minimally invasive tools (e.g. flexibleendoscopy), the devices will save valuable OR time, and also lead tofaster recoveries for patients. Furthermore, when used in the GI tractthe devices do not have to be recovered in a separate procedure becausethe devices pass naturally through the GI tract.

Methods of forming the magnetic anastomosis devices are also describedherein. The devices are simple to construct. First, the shape metal ispatterned and shape-set to form an exoskeleton. Next, the exoskeleton iscooled and opened prior to inserting cooled mitered magnets inside theexoskeleton. Finally, the device is allowed to return to roomtemperature, whereupon the shape metal regains its resilience. In someembodiments, an adhesive is added to secure the magnets. Specificdevices for shaping and opening the exoskeletons are also described.

BRIEF DESCRIPTION OF THE DRAWINGS

Other aspects, advantages and novel features of the invention willbecome more apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawingswherein:

FIG. 1 shows a magnet assembly delivered through an endoscope instrumentchannel such that the individual magnets self-assemble into a largermagnetic structure—in this particular case, an octagon;

FIG. 2A shows magnet assemblies that have been delivered and deployed toadjacent tissues;

FIG. 2B shows the two magnet assemblies coupled together by magneticattraction, capturing the intervening tissue. In some instances, theendoscope can be used to cut through the circumscribed tissue;

FIG. 3 shows several potential anatomical targets for anastomosisformation: Arrow A is stomach to small intestine, Arrow B is smallintestine to large intestine, Arrow C is small intestine to smallintestine, Arrow D is large intestine to large intestine, and Arrow E isstomach to large intestine;

FIG. 4A shows one embodiment of delivery using two endoscopes(colonoscope and enteroscope or gastroscope) to deliver magnetassemblies;

FIG. 4B shows another embodiment of delivery using two upper endoscopesboth sharing per-oral entry to deliver magnet assemblies;

FIG. 5 shows another embodiment of delivery using a single endoscope tosequentially deliver magnet assemblies;

FIG. 6 shows another embodiment of delivery using endoscopic ultrasoundguided needle delivery of one magnet assembly into lumen #1 followed bydeployment to of the second magnet assembly in lumen #2;

FIG. 7 shows the creation of a preliminary anastomosis to serve as aconduit for deeper endoscope delivery in order to create subsequentmultiple anastomoses;

FIG. 8 shows laparoscopic magnet device delivery into a lumen (stomach,in this example);

FIG. 9A shows endoscopic ultrasound guided needle delivery of a magnetassembly into the gallbladder which then couples with a second magnetassembly in the stomach or duodenum as shown in FIG. 9B;

FIG. 9B shows a magnet assembly in the gallblader coupled to a secondmagnet assembly in the stomach or duodenum following endoscopicultrasound guided needle delivery of each magnet assembly.

FIG. 10 shows stent deployment between the gallbladder and either thestomach or duodenum;

FIG. 11 shows another embodiment of an intra-gallbladder magnet assemblythat is a balloon that fills with fluid, gas, or magnetic material. Thisballoon is tethered to the endoscope and is initially delivered throughan endoscopic ultrasound guided needle;

FIG. 12 shows endoscopic ultrasound guided needle delivery of a magnetassembly into the bile duct;

FIG. 13 shows magnet assembly delivery into the bile duct throughendoscopic retrograde cholangiopancreatography techniques;

FIG. 14 shows coupling of the intra-bile duct magnet assembly with asecond magnet assembly deployed either in the stomach (A) or duodenum(B);

FIG. 15 shows another embodiment of bile duct magnetic anastomosis inwhich a hinged magnetic bile duct stent swings back onto itself bymagnetic attraction to form an anastomosis between the bile duct andduodenum;

FIG. 16 shows a magnetic stent that can be delivered into the pancreaticduct. The stent can be coupled with a magnet in the stomach (A) or inthe duodenum (B) to create a drainage anastomosis for the pancreaticduct;

FIG. 17 shows a magnetic assembly that is delivered into aperipancreatic collection (dotted structure) using endoscopic ultrasoundguided needle/catheter delivery which then couples with a second magnetassembly deployed in the stomach;

FIG. 18 shows different targets for anastomoses between the urinarysystem and the gastrointestinal system: renal calyx (A), ureter (B), andbladder (C);

FIG. 19 shows magnet assemblies in adjacent blood vessels to couple andcreate a vascular anastomosis;

FIG. 20 shows magnet assemblies in different parts of the respiratorysystem to create anastomoses between adjacent bronchioles;

FIG. 21 shows an external magnet assembly and an internal magnetassembly within the gastrointestinal tract used to create a surgicalstoma for fecal drainage;

FIG. 22 shows an endoscopically delivered magnet assemblies used toclamp off the base of superficial early gastrointestinal cancer to allowfor clean resection and automatic sealing of the resection site;

FIG. 23 is a view of an octagonal ring magnet in its deployed state;

FIG. 23A is a radial section through one segment's midpoint;

FIG. 23B is the same radial section through a segment comprising anexoskeletal member that fully envelopes the magnetic segments;

FIG. 24 is a view of an octagonal ring magnet in its deliveryconfiguration beginning to deploy from within a delivery lumen;

FIG. 25 is a graphic representation of the magnetic structure of theoctagonal ring magnet, where shading represents opposite poles of thealternating magnetic dipole pattern of the segments;

FIG. 26A shows eight octagon mitered segments magnetically assembled(right) next to a shape-set nickel titanium octagonal exoskeleton (left)of 0.1 mm thick superelastic sheet;

FIG. 26B illustrates that the gap in the exoskeleton can be placed intwo different positions. When assembled, a matched set of two deviceswith gaps in different positions will not be able to have alignedopenings;

FIG. 26C shows an alternative construction in which the exoskeleton isnot a continuous piece, but rather a collection of exoskeleton piecesproviding structural guidance to the magnetic assemblage;

FIG. 27 shows a metastable assemblage of seven magnetic segments held bymagnetic attraction at the mitered joints;

FIG. 28 shows an initial shape photoetched from 0.1 mm thick nitinolsheet;

FIG. 29 shows the deformation of a patterned nitinol piece formed from athin-walled circular tube. The newly shaped exoskeleton has a roughlysquare cross section;

FIG. 30 shows two octagonal ring magnets interacting and demonstratesthe various configurations of ring opening arrangement;

FIGS. 31A-B depict assembly of an eight segment shape metal exoskeletonand magnet assembly. FIG. 31A shows the shape metal exoskeleton andmagnet assembly prior to wrapping the exoskeleton over the magnetassemblage. FIG. 31B shows a completed magnetic anastomosis device withshape metal exoskeleton;

FIGS. 32A-B show an exemplary opening device for opening the shape metalexoskeleton to allow the exoskeleton to be placed over the magnetassembly. FIG. 32A shows the opening device in a closed position,suitable for loading a formed shape metal exoskeleton. FIG. 32B showsthe opening device in an open position, suitable for opening a formedshape metal exoskeleton. In some embodiments, the shape metalexoskeleton is opened with an opening device in a bath of cold ethanol;

FIGS. 33A-B show the process of opening a formed shape metal exoskeletonprior to placing it on a magnet assembly. In FIG. 33A, a formed shapemetal exoskeleton in a pinched configuration is placed on a closedopening device. In FIG. 33B, the formed shape metal exoskeleton isopened;

FIG. 34 shows an octagonal ring magnet with dipole, quadrupole andhexapole segments;

FIG. 35 shows a square of dipoles and quadrupoles;

FIG. 36 shows a square of alternating dipoles;

FIG. 37 shows potential energy plots for the juxtaposition of variousmagnetic polygons;

FIG. 38 shows the photoetch pattern for a segmented exoskeleton;

FIG. 39 shows FIG. 38 shape set into a channel by heating the materialin an inert atmosphere and then quenching;

FIG. 40 shows two external NiTi exoskeletal and two internal NiTiexoskeletal structures before adhesive assembly to magnet segments;

FIG. 41 shows exoskeletal structures with various magnetic polarities inthe six polygonal multipolar segments;

FIG. 42 shows an assembly as in FIG. 39 emerging from a rectangularchannel;

FIG. 43 depicts the geometry of the peripheral metallic ring of theexoskeleton at one miter joint between magnetic segments in bothdelivery and deployed configuration;

FIG. 44 shows a magnetically regular, physically irregular hexagonalring magnet;

FIG. 45 shows a complex octagonal ring magnet comprising dipoles,quadrupoles and hexapoles;

FIG. 46 shows potential energy variations as a function of rotationalorientation of two octagonal ring magnets in FIG. 45;

FIG. 47 shows an octagonal device constructed from four shorter piecescomprising only two linked magnetic segments each. Integral loopstructures reinforce the exoskeleton and provide means for manipulationthe device during deployment;

FIG. 48 depicts two embodiments showing use of nitinol wire or braidedDyneema™ or polyester to provide tensile reinforcement and means ofmanipulation;

FIG. 49 shows a raised feature or protruding element (25) that can beincorporated to increase pressure on a tissue by reducing the contactarea against the tissue;

FIG. 50A shows an embodiment, where the exoskeletal structure on thepreferred side of passage is slightly larger in size than its matingexoskeletal structure. Additional material (28) has been added toestablish this as the preferred side of passage as the devices disengagefrom the tissue;

FIG. 50B illustrates that additional magnetic material (29) can be addedto determine the direction in which the coupled assembly disengages fromthe tissue;

FIG. 51A shows the containment tube packaging with pre-loadedexoskeletal structure to facilitate easy channel insertion;

FIG. 51B shows a deployment rod pushing the exoskeletal structure intoan endoscope port;

FIG. 52A shows a deployment rod with an internal channel through whichthe exoskeletal structure sutures can be passed;

FIG. 52B shows a deployment rod with a mitered end that reversiblyattaches to the proximal end of a magnetic anastomosis device duringdeployment;

FIG. 53 illustrates how device placement can be directed by applyingtension to sutures 1 and 2;

FIG. 54 shows a dual channel endoscope and the use of a grasper toremove a device by exerting force against the opposing suture attachmentpoints;

FIG. 55 shows an embodiment of a device having channels in the terminalmagnet segment and holes in the exoskeleton to allow passage of ahigh-strength suture or other connection to provide better openingleverage;

FIG. 56 is a schematic illustration of the gallbladder, generallyillustrating the positioning of parent and daughter magnets to create acompression anastomosis, and particularly, the delivery of daughtermagnetic material through a biliary catheter to the gallbladder;

FIGS. 57A-57E are radiographic views illustrating the deployment andretrieval of parent and daughter magnets to create an anastomosisbetween the gallbladder and the stomach;

FIGS. 58A-58D are schematic views of a plurality of magnets in the lumenof a catheter, illustrating the process of magnetic self-assembly as themagnets are ejected from the catheter;

FIG. 59 depicts the arrangement for self-alignment between assembledparent and daughter magnets using north/south attractive magnet forces;

FIG. 60 depicts the arrangement for self-alignment between assembledparent and daughter magnets, using “east/west” attractive magneticforces;

FIGS. 61A-61D illustrates the concept of “Magnet Self Assembly” in aconnected train of magnetic components including a combination ofquadruple and dipole components;

FIG. 62 depicts the extrusion of magnet components arranged in“North-South” arrangement from a fine needle aspiration (FNA) needle;

FIG. 63 depicts the self-assembly of the magnetic components depicted inFIG. 62 after extrusion from FNA needle and the use of a suture toconnect the magnetic components;

FIG. 64 depicts the deployment of daughter magnets from the stomach intothe gallbladder using endoscopic ultrasound, the assembly of thedaughter magnets in the gallbladder, and the positioning of a suture inthe stomach upon retraction of the endoscopic ultrasound scope;

FIG. 65 depicts the assembly of daughter magnets in the gallbladder, thedeployment and assembly of a parent magnet in the stomach, and thepositioning of a suture connecting the daughter magnet assembly and theparent magnet assembly;

FIG. 66 depicts the magnetic attraction of daughter magnet assemblypositioned against the wall of a gallbladder and a parent magnetpositioned against an adjacent stomach wall.

DETAILED DESCRIPTION

Self-assembling magnetic anastomosis is a promising therapeutic modalitybecause it addresses several of the historical disadvantages oftraditional anastomosis (discussed in Background). It allows asurgical-quality anastomosis in a minimally-invasive fashion, heretoforenot possible. As described below, the invention includes devices havinga plurality of small magnets that can be delivered endoscopically orlaparoscopically through a delivery conduit (such as an endoscope,laparoscope, catheter, trocar, or other delivery device) whereby theyreproducibly re-assemble into a larger magnet structure in vivo.

As described herein, the magnetic devices are relatively smooth and flatand have essentially uninterrupted annular faces. Because of thisdesign, the devices do not cut or perforate tissue but rather achieveanastomosis by providing steady necrotizing pressure across the contactsurface between mating polygonal rings. Because the devices includeexoskeletons that direct self-assembly, the devices consistentlyself-assemble into the correct shape upon deployment, which greatlyreduces the risks of surgical complications due to misshapen devices orpremature detachment. These features also reduce the risks associatedwith surgical access and ensure that the anastomosis is formed with thecorrect geometric attributes. Overall, this ensures the patency of theanastomosis. In some embodiments, the exoskeleton is formed from a shapemetal, e.g., nitinol.

As described in greater detail below, the invention discloses flexiblelinear magnetic devices comprising linked magnetic multipole segmentsthat, when extruded from the end of a deployment channel or lumen,self-assemble to form a rigid, multipolar polygonal ring magnet (PRM;generally “magnetic device”). The self-assembly is directed by anexoskeleton that is capable of returning to a pre-determined shape. Insome embodiments, the exoskeleton is formed from a shape metal, e.g.,nitinol. The physical and magnetic structure of the deployed magneticdevices is such that when two magnetic devices approach one another,there is a rapidly strengthening attractive magnetic interaction, whichcreates a coupling between the magnetic devices. In some instances, itis necessary to pre-align the complimentary devices, however, in otherinstances the devices self-align by undergoing fast in-plane rotationwith respect to one another, as discussed in detail below. As describedin detail below, systems including the magnetic devices may include anendoscope having sensors that allow the endoscope to sense the positionof a mating magnetic device or another endoscope that will deploy themating device.

In some embodiments, the magnetic anastomosis devices comprise shapemetal, e.g., shape metal alloys (i.e. memory metal alloys) exoskeletonsand mitered segments of rare earth magnets of very high coercivity,e.g., as illustrated in FIG. 23. Connecting each of the alternatingdipolar segments to a single exoskeleton produces a well-behaved,self-erecting and self-closing flexible structure that can be deliveredthrough a small orifice, such as the delivery channel of an endoscope(see, e.g., FIGS. 1 and 24). As each successive magnetic segment emergesfrom the end of the guiding channel into the organ lumen, theexoskeleton constrains the segment against out-of-polygonal planedeflection and the segments' mutual attractions close each miter jointin the correct inward direction, sequentially correct and, as the lastsegment is extruded, to close the polygonal magnetic ring. Although theexoskeletal bias and out-of-polygonal-plane stiffness is important forguiding the miter closure, the principle motive and retentive force isthe magnetic attraction of the miter surfaces, by virtue of theiropposite magnetic polarity. The strength of this interaction, i.e., thedepth of the potential energy well into which the attracted surfacesfall, contributes to the physical integrity and stability of thepolygonal ring magnet device. Furthermore, when the devices areconstructed with symmetric miter joints and have their magnetic polesaligned with the annular axis of the polygon, the total magnetic forcenormal to the mating surfaces is maximized. The magnetic forces increasethe mechanical stability of a set of coupled magnets while speedinganastomosis formation due to the intense compressive force on thetrapped tissues.

During deployment, the exoskeletal hinge between magnetic segmentscouples the structural rigidity of individual segments similar to acantilevered beam. In other words, the tensile modulus of theexoskeleton and the exoskeleton's resistance to out-of-plane bendingallow the forces on the distal end of the structure to be distributedacross the magnetic segments. The design allows a pushing force on theproximal end of the device to reliably move the distal end of thedevice, e.g., out of the deployment lumen. Because the exoskeleton isthin and in close contact with the magnetic segments that are longrelative to the length of the miter joint, the exoskeleton can bend toaccommodate miter closure with relatively small strain. However, thebreadth of the exoskeleton produces a high moment of inertia (stiffness)against out-of-polygonal-plane bending, thereby giving good guidance ofthe growing ring and providing lateral resistance to deflection duringclosure. Finally, the exoskeleton also provides a tensile couplingbetween the magnetic segments, assuring that the segments do not go pastthe closure point and collapse inward or over top of one-another.

Surgical Applications

When deployed in adjacent tissues, for example adjacent organs ordifferent regions of the same organ, the coupled magnetic devices createa compressive ring that can be surgically opened, or allowed to form ananastomosis without further intervention. When paired devices are leftalone, the compressive force against the tissues collapse thevasculature and extrude fluids in the tissues, further reducing thedistance between the devices and increasing the magnetic attraction.With time, the coupled devices eventually couple completely and fallaway, leaving a formed anastomosis. This cascade begins when the devicesapproach within “capture range,” whereby their mutually-attractiveforces are sufficient to align the devices, trap the intervening tissue,and resist the natural pliancy of the tissues as well as the motion ofthe tissue under normal physiologic function.

Overall, the design specifications of the devices depend on the patientand the intended anastomosis. The design specifications may include:required capture range, desired effective inner and outer diameters ofthe deployed polygonal rings (e.g., as defined by the desiredanastomosis size and instrument passage), thickness of the targettissue, and the inner diameter of guiding channel and the smallestradius of curvature to which the guiding channel may be bent and throughwhich the magnets must pass. Once the design specifications are chosen,corresponding magnetic device designs can be determined, such aspolygon-side-count and length, and the maximum lateral dimensions of theflexible linear magnetic structure that will be deployed through thedelivery instrument.

Deployment of a device of the invention is generally illustrated inFIG. 1. When used with the techniques described herein, the devicesallow for the delivery of a larger magnetic structures than wouldotherwise be possible via a small delivery conduit, such as in astandard endoscope, if the devices were deployed as a completedassembly. Larger magnet structures, in turn, allow for the creation oflarger anastomoses that are more robust, and achieve greater surgicalsuccess. Because the magnetic devices are radiopaque and echogenic, thedevices can be positioned using fluoroscopy, direct visualization(trans-illumination or tissue indentation), and ultrasound, e.g.,endoscopic ultrasound. The devices can also be ornamented withradiopaque paint or other markers to help identify the polarity of thedevices during placement. In some embodiments, the devices can bepositioned by use of sensors located in proximity to the delivery lumenand able to sense the position of a mating device, e.g., using a Reedswitch or a Hall-effect sensor.

In general, as shown in FIG. 2A, a magnetic anastomosis procedureinvolves placing a first and a second magnetic structure adjacent totargeted tissues, thus causing the tissues to come together. Themagnetic devices are deployed so that that opposite poles of the magnetswill attract and bring the tissues together. The two devices may both bedeployed inside the body, or one may be deployed inside the body and theother outside the body. Once the magnets have been deployed, the tissuescircumscribed by the magnetic structures can be cut to provide animmediate anastomosis, as shown in FIG. 2B. In other embodiments, thetissues circumscribed by the devices will be allowed to necrose anddegrade, providing an opening between the tissues. While the figures andstructures of the disclosure are primarily concerned with annular orpolygonal structures, it is to be understood that the delivery andconstruction techniques described herein can be used to make a varietyof deployable magnetic structures. For example, self-assembling magnetscan re-assemble into a polygonal structure such as a circle, ellipse,square, hexagon, octagon, decagon, or other geometric structure creatinga closed loop. The devices may additionally include handles, sutureloops, barbs, and protrusions, as needed to achieve the desiredperformance and to make delivery (and removal) easier.

As described with respect to the figures, a self-assembling magneticanastomosis device can be placed with a number of techniques, such asendoscopy, laparoscopy, or with a catheter (e.g. not with directvisualization, fluoro, etc.). Regardless of method of device delivery,it is important to note that the procedure for creating the anastomosiscan be terminated without perforation of tissue after confirmation ofmagnet coupling. As described previously, the compression anastomosisprocess can be allowed to proceed over the ensuing days, resulting inthe natural formation of an opening between the tissues. The fusedmagnets can either be allowed to expel naturally or the magnets can beretrieved in a follow-up surgical procedure. Alternatively, if immediatebypass is required, the tissues circumscribed by the magnets can be cutor perforated. Perforation can be accomplished with a variety oftechniques, such as cautery, microscalpel, or balloon dilation of tissuefollowing needle and guidewire access.

In some embodiments, the self-assembling magnetic devices are used tocreate a bypass in the gastrointestinal tract. Such bypasses can be usedfor the treatment of a cancerous obstruction, weight loss or bariatrics,or even treatment of diabetes and metabolic disease (i.e. metabolicsurgery). Such a bypass could be created endoscopically,laparoscopically, or a combinations of both. FIG. 3 illustrates thevariety of gastrointestinal anastomotic targets that may be addressedwith the devices of the invention: stomach to small intestine (A),stomach to large intestine (E), small intestine to small intestine (C),small intestine to large intestine (B), and large intestine to largeintestine (D). In an endoscopic procedure, the self-assembling magneticdevices can be delivered using two simultaneous endoscopes, e.g., anupper endoscope or enteroscope residing in the upper small intestine,and a colonoscope residing in the lower small intestine, as shown inFIG. 4A. Alternatively, as shown in FIG. 4B, two simultaneous upperendoscopes (one residing in the stomach and the second in the smallintestine) can be used to place the devices. In other embodiments, theself-assembling magnets can be delivered sequentially through the sameendoscope, which has been moved between a first deployment position anda second deployment position. For example, in FIG. 4A, a single per-oralendoscope could deliver and deploy one self-assembling magnet in thesmall intestine, withdraw, and then deploy the second reciprocal magnetin the stomach. Again, magnet coupling would be confirmed usingfluoroscopy. FIG. 5 illustrates removal of a single endoscope afterplacement of two magnetic devices.

A variety of techniques can be used to detect the first deployedmagnetic device to assist placement of the second mating structure. Oncethe first device is deployed at the desired anastomotic location, thetwo deployed magnetic devices need to find one another's magnetic fieldso that they can mate and provide the compressional force needed toprompt formation of an anastomosis. Ideally, the frames can be roughlylocated within several cm of one another (e.g., using ultrasound), atwhich point the magnets will self-capture and self-align. Where this isnot possible, one of the following techniques can be used. A firstlocation technique involves a direct contact method using twoendoscopes. Here an endoscope's displacement in an adjacent lumencreates a displacement seen by another endoscope in the adjacent lumen.The displacement identifies a potential intersection point for ananastomosis location. For example, a magnetic deployment tool (describedbelow) will be deflected by the presence of a deployed device on theother side of a tissue wall.

The second location technique involves trans-illumination, whereby highintensity light from one endoscope is directed at the lumen wall of theproposed anastomosis site. Using this technique, another endoscope inthe adjacent lumen looks for the light, which diffuses through the lumenwall and projects onto the wall of the adjacent lumen. This lightrepresents the potential intersection anastomosis point. A cap or lenscan also be placed over the light emitting endoscope to furtherintensify and pinpoint the proposed intersection point. A similartechnique could use radio-wave- or ultrasound-transducers and receiversto collocate the endoscope tips. In some embodiments, a system mayinclude an endoscope having a sensor and a magnetic anastomosis devicefor deployment using the endoscope.

A third location technique involves magnetic sensing techniques todetermine the proximity of the deployed ring magnet in the adjacentlumen. By maximizing the magnetic field being sensed, the minimumdistance between the adjacent channels can be identified. The magneticsensor can be carried on a probe inserted down the working channel ofthe endoscope and utilize common magnetic sensing technology such as aHall Effect Sensor or Reed switch.

With trans-illumination and magnetic sensing, an additional accessorymay also assist with delivering magnetic devises to a preciseanastomosis site. A radially expanding ring structure can be deployedwith the endoscope or laparoscope that can press fit and seat itself onthe scope's outer diameter. The outer diameter of this expanding elementis sized to allow the deployed device to seat itself on this expandingelement (again likely a press fit). With this expanding element andmagnetic device radially seated about the endoscope axis, the endoscopecan be directed to the ideal anastomotic location through directcontact, trans-illumination, or magnetic sensing, and then the matingmagnet device released when the anastomosis site is identified.

In other embodiments, the self-assembling magnet devices would bedelivered using ultrasound guidance, e.g., endoscopic ultrasound. Forexample, using an echoendoscope in the stomach, a suitable smallintestine target could be identified. As shown in FIG. 6, a deliveryneedle 600 (e.g., an aspiration needle) or catheter can be used toaccess to the small intestine target and deliver the self-assemblingmagnets into the small intestine lumen. The delivery can be guided withfluoroscopy or endoscopic ultrasound. Following self-assembly, thesesmall intestine magnets would couple with a second set of magnetsdeployed in the stomach. The two devices can be delivered with the sameneedle or with different needles. It is also possible to deliver thefirst device with an endoscope and the second device with a needle orvice versa.

In another embodiment, illustrated in FIG. 7, a first anastomosis,created in an initial procedure, can be used to provide access for thecreation of a second anastomosis. This process could theoretically berepeated multiple times to create additional anastomoses. For example, agastrojejunal anastomosis (stomach to mid-small intestine) could serveas a conduit for the creation of a second, more distal gastrojejunalanastomosis. Ultimately, in this particular scenario, the stomach wouldhave several bypasses to the small intestine. Additionally, in someinstances, more anastomoses could be added to “titrate” to a specificclinical effect (e.g. lower glycosylated hemoglobin in type 2 diabetes).In alternative embodiments, an anastomosis may be placed to give accessfor a different type of surgery, e.g., tumor removal.

In another embodiment of delivery, the self-assembling magnets could bedelivered laparoscopically through a surgical incision into the targetorgans (e.g., stomach and small intestine) and allowed to couple tocreate an anastomosis, as shown in FIG. 8. Again, this procedure couldbe directed with fluoroscopy or ultrasound and the procedure can bepurely laparoscopic, or a combination of endoscopic and/or laparoscopicand/or needle procedures.

Gastrointestinal anastomoses can be used to address a number ofconditions. An anastomosis or series of anastomoses between the proximalbowel and distal bowel may be used for treatment of obesity andmetabolic conditions, such as Type II diabetes and dyslipidemia. Theprocedure can also be used to induce weight loss and to improvemetabolic profiles, e.g., lipid profiles. The bowel includes any segmentof the alimentary canal extending from the pyloric sphincter of thestomach to the anus. In some embodiments, an anastomosis is formed tobypass diseased, mal-formed, or dysfunctional tissues. In someembodiments, an anastomosis is formed to alter the “normal” digestiveprocess in an effort to diminish or prevent other diseases, such asdiabetes, hypertension, autoimmune, or musculoskeletal disease.

Using the self-assembling magnetic devices of the invention, it ispossible to create a side-to-side anastomosis that does not requireexclusion of the intermediate tissues, as is common withstate-of-the-art bariatric procedures. That is, using the devices of theinvention (or other means for creating an anastomosis) it is possible tocreate an alternate pathway that is a partial bypass for fluids (e.g.,gastric fluids) and nutrients (e.g., food), while at least a portion ofthe old pathway is maintained. This design allows the ratio of “normal”to “modified” digestion to be tuned based upon the goals of theprocedure. In other words, using the described procedure, a doctor canchoose the ratio of food/fluids shunted down the new (partial) bypassversus food/fluids shunted down the old pathway. In most instances, thefraction shunted down the bypass limb will drive the patient toward thedesired clinical endpoint (e.g. weight loss, improvement in glycosylatedhemoglobin, improvement in lipid profile, etc.) The mechanism by whichthe endpoints are achieved may involve early macronutrient delivery tothe ileum with stimulation of L-cells and increase in GLP-1 production,for example. The mechanism may also involve loss of efficiency ofnutrient absorption, especially glucose, thereby reducing blood glucoselevels. At the same time, however, the fraction shunted down the oldpathway protects against known metabolic complications that can beassociated with bariatric surgery such as excessive weight loss,malabsorptive diarrhea, electrolyte derangements, malnutrition, etc.

To achieve a desired ratio of bypass (e.g. re-routing food andsecretions to flow down the new pathway, say, 70% or 80% or 90% or 100%of the time), the size, location, and possibly number of anastomoseswill be important. For example, for a gastrojejunal anastomosis, it maybe critical to place the anastomosis in a dependent fashion to takeadvantage of the effects of gravity. Also, instead of a roundanastomosis, it may be better to create a long, oval-shaped anastomosisto maximize anastomotic size. Alternatively, multiple gastrojejunalanastomoses may be used to titrate to a certain clinical endpoint (e.g.,glycosylated hemoglobin in Type II diabetes). Most of the proceduresdescribed herein may be used to place one or more anastomoses, asneeded, to achieve the desired clinical endpoint. For example, the twoendoscope procedures illustrated in FIGS. 4A and 4B can be used tocreate a partial bypass of a portion of the bowel. Based upon thedesired ratio of bypassed and non-bypassed nutrients, the anastomosesshown in FIGS. 4A and 4B can be made larger, e.g. greater than 1 cm inopen diameter, or several smaller anastomoses can be placed to achievethe desired ratio.

The procedure is also adjustable. For example, a first anastomosis maybe formed and then, based upon clinical tests performed after theprocedure, one or more anastomoses can be added to improve the resultsof the clinical tests. Based upon later clinical results, it may benecessary to add yet another anastomosis. Alternatively, it is possibleto partially reverse the condition by closing one or more anastomosis.Because the partially bypassed tissues were not removed, they can returnto near normal functionality with the passage of greater amounts ofnutrients, etc. The anastomoses may be closed with clips, sutures,staples, etc. In other embodiments, a plug may be placed in one or moreanastomoses to limit the ratio of nutrients that traverse the “normal”pathway. Furthermore, it is possible to close an anastomoses in onelocation in the bowel and then place a new anastomosis at a differentlocation. Thus is possible to generally and tunably create a partialbypasses, or a series of partial bypasses, between portions of the bowelto achieve clinical endpoints, e.g., as described in FIG. 3.

The described procedures may also be used with procedures that remove orblock the bypassed tissues, as is common with bariatric procedures. Forexample, a gastrojejunal anastomosis may be coupled with a pyloric plug(gastric obstruction) or another closure of the pylorus (e.g. suturedclosure) to shunt food completely down the new bypass. Such procedurescan be used, for example, to bypass tissue that is diseased, e.g.,because of cancer.

In another category of procedures, endoscopic ultrasound (EUS) can beused to facilitate guided transgastric or transduodenal access into thegallbladder for placement of a self-assembling magnetic anastomosisdevice. Once gallbladder access is obtained, various strategies can beemployed to maintain a patent portal between the stomach and thegallbladder or the duodenum and the gallbladder. In another embodiment,gallstones can be endoscopically retrieved and fluid drained. Forexample, using the described methods, an anastomosis can be createdbetween the gallbladder and the stomach. Once the gallbladder isaccessed in a transgastric or transduodenal fashion, the gallstones canbe removed. Furthermore, the gallbladder mucosa can be ablated using anynumber of modalities, including but not limited to argon plasmacoagulation (APC), photodynamic therapy (PDT), sclerosant (e.g.ethanolamine or ethanol).

One strategy for creation of a portal is to deploy self-assemblingmagnets via an endoscopic needle under ultrasound guidance into thegallbladder and also into the stomach or duodenum. These magnets willmate and form a compression anastomosis or fistula. A second strategyfor creation of a portal is to deploy self-assembling magnets via anendoscopic needle 600 as shown in FIGS. 9A and 9B. While the coupledmagnetic assemblies are shown as octagons, the closed frame could takethe shape of any polygonal structure, e.g., a square, a circle, atriangle, hexagon, heptagon, nonagon, decagon, dodecagon, etc. One suchdevice would be deployed into the gallbladder, and the mating devicewould be deployed into the stomach or duodenum. In the same fashion asdiscussed above with respect to gastrointestinal deployment, the tissuecircumscribed by the two magnetic devices can be cut with cautery,microscalpel, needle-knife, or other deployable cutting mechanism. Inanother embodiment, the coupled tissues can be left to necrose and formthe anastomosis.

The devices need not be limited to forming holes, however. Otherstructures can be coupled to one or more mating magnetic devices tocreated additional functionality. For example, a stent could be deployedbetween tissues, such as the gallbladder and the stomach, as shown inFIG. 10. Alternatively, the gallbladder magnet could be coupled to aballoon-based device that fills with air, fluid, magnetic pieces ormagnetic particles. Upon inflation, the balloon would serve as an anchorin the bile duct following placement. The balloon could also have anannular configuration to allow for immediate access after coupling withthe second magnet. See, e.g., FIG. 11. Regardless of embodiment,however, it is critical to contain the original access pathway withinthe confines of the coupled magnets, i.e., not leaving a pathway for theescape of bile. Otherwise, the opening will allow bile leakage that canresult in peritonitis.

Another medical application for self-assembling magnets is directbiliary access. Currently, to achieve decompression for a malignantbiliary stricture, endoscopic retrograde cholangiopancreatography (ERCP)is performed. The biliary tract is accessed endoscopically through thepapilla in retrograde fashion and a stent is deployed across thestricture over a guidewire. These stents frequently require subsequentprocedures for exchange, clean-out, or placement of additionaloverlapping stents. The need for exchange and cleaning is required tocounteract the high rate of infection of the biliary tree (i.e.cholangitis) when using an ERCP procedure. Because of the high rate ofmorbidity, ERCP is typically limited to patients that have no otheroption to address pancreatic disease.

Using devices of the invention, however, it is possible to easily forman anastomosis between the bile duct (preferably the main bile duct) andeither the duodenum or the stomach (choledocho-gastric andcholedocho-duodenal anastomoses, respectively). This anastomosis ispermanent and typically does not require intervention if located apartfrom the diseased tissue. In an embodiment, a biliary magnetic device isdelivered directly into the bile duct under endoscopic ultrasoundguidance. As described below, the self-assembling magnetic device isextruded through a needle or catheter, whereupon it deploys in thecorrect configuration. Using fluoroscopy or ultrasound, it is thenpossible to confirm that the device has self-assembled and is in thecorrect location. In some embodiments, the magnetic device may betethered to the delivery needle or catheter by means of a detachablewire or suture to enable mechanical retraction until optimal positioningis confirmed.

In one embodiment, the magnetic device can be delivered endoscopicallyto the bile duct via wall of the duodenum, as shown in FIG. 12. Inanother embodiment, the biliary magnet can be delivered in conventionalretrograde fashion through the ampulla into the bile duct, as shown inFIG. 13. One benefit of retrograde delivery is that it avoids needlepunctures across tissue planes, as is the case with the deploymentmethod shown in FIG. 12. Regardless of the method for delivering thebiliary magnets, however, a second magnetic device is required in eitherthe gastric (A) or duodenal (B) lumen, as shown in FIG. 14. Typicallythis decision is dependent upon the patient's anatomy (e.g., size of theduodenal lumen) and the location of the initial biliary magnet. Inscenarios based on endoscopic ultrasound needle delivery, the secondmagnetic device can be connected to the biliary magnet via theaforementioned detachable wire, and therefore extruded through the samedelivery needle/catheter. Alternatively, the second device can bepre-attached to the exterior of the endoscope and slid into position forcoupling after biliary magnet deployment. The latter procedure may bemore applicable to forward-viewing echoendoscopes but may be used withendoscopes, generally.

In another embodiment, the biliary magnet is a balloon-based device thatfills with air, fluid, magnetic pieces or magnetic particles, similar topreviously described with respect to gallbladder procedures. Uponinflation, the balloon would serve as an anchor in the bile ductfollowing placement. In an embodiment, the balloon could have an annularconfiguration to allow for immediate access after coupling with thesecond magnet. Additionally, like the gallbladder procedures describedabove, a biliary magnetic device can be used with a stent form-factor.In an embodiment, the stent has an internal biliary magnet and a hingedexternal magnet. The stent can be inserted in retrograde fashion throughthe ampulla into the bile duct. The hinged external magnet can then beswung around and coupled with the internal biliary magnet to form afistula between the bile duct and the duodenum, as shown in FIG. 15.

The magnetic devices of the invention can also be used to treatpancreatic diseases. For example, the pancreatic duct requiresdecompression in certain disease states, such as chronic pancreatitis.Currently, extensive pancreatic duct decompression requires surgery(e.g. Peustow surgery in which the pancreas is filleted along the axisof the pancreatic duct and connected to a loop of small intestine forimproved pancreatic drainage). As an alternative to Peustow surgery,extensive pancreatic duct decompression can be accomplished via creationof a large magnetic compression anastomosis between the pancreatic ductand either the stomach or duodenum using a magnetic pancreatic catheter,as shown in FIG. 16. The catheter can be magnetic along its entirelength or only at certain intervals. The catheter can be in the form ofa stent or straw. The pancreatic duct can be accessed using conventionalERCP methods (retrograde cannulation through the ampulla) or by directneedle access using endoscopic ultrasound (EUS). The magnetic pancreaticcatheter can be delivered into the pancreatic duct and coupled with asecond magnetic device in either the stomach or duodenum. As in thebiliary scenario described above, the magnetic pancreatic catheter couldbe hinged to the second magnetic device.

Self-assembling magnetic devices can also be used to access and drainfluid collections located adjacent to the gastrointestinal tract, asshown in FIG. 17. For example, following a bout of pancreatitis,pancreatic fluid collections can form that require drainage. Whiledrainage can be accomplished using surgery or a percutaneous catheter,endoscopic drainage has been found to be more clinically andcost-effective, but can be complicated by bleeding, perforation, and/orinadequate drainage. As an alternative to surgical draining, magneticdevices of the invention can be delivered through a needle or sharpenedcatheter into the collection under endoscopic ultrasound (EUS) guidance,as shown in FIG. 17. Following assembly, the first magnetic device iscoupled to the second magnetic device that has been placed in thegastrointestinal lumen (e.g. stomach). In order to speed removal afterdrainage, the first magnet may be tethered by a connecting wire aspreviously described. As described previously, the intervening tissuecan be cut using electrocautery or dilation followed by needle and wireaccess. Additional devices, such as magnetic coupling clamps can be usedto control blood flows to allow for “blood-less” endoscopic entry intothe collection.

Self-assembling magnets can also be used for urological applicationssuch as forming bypasses to treat an obstructed urogenital tract, asshown in FIG. 18. For example a magnetic anastomosis could be createdbetween the renal calyx and bowel (A), between the ureter and bowel (B),or between the bladder and bowel (C). Self-assembling magnetic devicesof the invention can be delivered into the urological tract using anendoscope, laparoscope, or needle, as described above. The reciprocalmagnetic device could be delivered into the gastrointestinal tract usingan endoscope, laparoscope, or needle as previously described. In otherembodiments, the devices can be used for reproductive procedures, suchas bypassing a portion of obstructed fallopian tube or bypassing avasectomy.

In yet another application, self-assembling magnetic devices can be usedto create vascular anastomoses or to treat cardiac conditions. Forexample, a magnetic anastomosis coupling can be formed between adjacentblood vessels with magnetic devices, as shown in FIG. 19. In anembodiment, the self-assembling devices can be delivered with a vasculardelivery device, such as a catheter. Additionally, as described abovewith respect to gallbladder and pancreatic applications, a shunt can beinstalled to bypass a portion of the vasculature that is weak orblocked.

Self-assembling magnets can also be used for pulmonary applications suchas forming bypasses in the airway to treat chronic obstructive pulmonarydisease (COPD). For example, magnetic anastomoses can be created bydeploying self-assembling magnetic devices into adjacent bronchioles, asshown in FIG. 20. Creation of pulmonary “bypasses” could lower airwayresistance that characterizes respiratory diseases such as COPD.

Self-assembling magnetic devices can also be used to create surgicalstomas for diversion of a fecal stream, e.g., into a colostomy bag. Forexample, a magnetic anastomosis can be created by deployingself-assembling magnets into the gastrointestinal tract (e.g. largeintestine), as shown in FIG. 21, and then coupling the interior magnetto an external magnet worn and secured at the level of the skin. Theexterior magnetic device may be coupled to yet a third magnetic devicethat is coupled to a collection device. Such a system allows easyremoval of the collection device for cleaning, etc.

In other embodiments, self-assembling magnets can be used to performdeep endoscopic full-thickness resections of cancerous or pre-cancerouslesions along with simultaneous closure of the resulting defects. Insome embodiments, the lesion can be tented with endoscopic traction toaccommodate placement of reciprocal magnets at the base of the lesion,as shown in FIG. 22. The lesion can be resected and retrieved above thecoupled magnets. The coupled magnets will eventually fuse and sloughoff, leaving behind a sealed resection site.

Materials and Methods of Manufacture

In general the magnetic anastomosis devices comprise shape metalexoskeletons and mitered segments of rare earth magnets of very highcoercivity, e.g., as illustrated in FIG. 23. Connecting each of thealternating dipolar segments to a single exoskeleton produces awell-behaved, self-erecting and self-closing flexible structure that canbe delivered through a small orifice, such as the delivery channel of anendoscope (see, e.g., FIGS. 1 and 24). As each successive magneticsegment emerges from the end of the guiding channel into the organlumen, the exoskeleton constrains the segment against out-of-polygonalplane deflection and the segments' mutual attractions close each miterjoint in the correct “inward” direction, to sequentially erect and, asthe last segment is extruded, to eventually close the planar polygonalmagnetic ring.

In an embodiment, the rare earth magnets comprise neodymium compounds,such as Nd_(x)Fe_(y)B_(z), and may be referred to interchangeably as“Neodymium,” “NIB,” or “Neo” magnets. The magnetic material is chosen tohave a very high energy product (BH_(max)), i.e., the density ofmagnetic energy, which results in very strong coupling between adjacentmagnets. The very high energy product allows the magnetic devices tohave maximal magnetic attraction despite having a small cross-sectionalsize. The small sizing is required to allow the structure to bedelivered down an endoscope, needle, or small lumen of a medicaldelivery device, e.g., as discussed above. Fortunately, neodymiummagnets are both radiopaque and echogenic, which makes it easy to locateand observe the devices with medical imaging techniques such asfluoroscopy and ultrasound.

The neodymium magnets are commercially available from suppliers such asDuraMagnetics, Inc. of Sylvania, Ohio. The magnets can be orderedpre-cut and finished, or the magnets can be cut with a wire EDM machineor ID slicer and finished with a surface grinder. Typically, very highmagnetic energy density magnets, such as N52 grade neodymium magnets,are used. After machining, the magnetic segments are typically plated toexclude oxygen from the reactive NIB. The plating is often predominantlynickel (either electrolytic or electroless) and often includes someamount of preplate etching, as well as an initial gold strike and afinal gold finish for biocompatibility. After plating, the magneticsegments are magnetized with north and south poles on the trapezoidalfaces. The magnetic segments are then assembled into a magneticassemblage and covered with an exoskeleton, as discussed below.

An octagonal magnetic anastomosis device is shown in FIG. 23. The devicecomprises magnetic segments 10, each with the long edges chamfered, 11,and surrounded on three sides by a shape metal exoskeleton 12, e.g., asuperelastic nickel titanium exoskeletal structure. The exoskeleton 12structure has one opening gap 13, and a continuous flat band 14surrounding the octagon's perimeter and forming a polygonal cylinderperpendicular to the plane of FIG. 23. The edge of continuous flat band14 is visible at each miter joint 15, where the mitered edges 17 ofevery flange 18 abut and close to form a smooth, continuous surface.Radius 16 provides for a section 19 of adequate length to control strainto the elastic or pseudoelastic limits of the shape metal. While notshown in FIG. 23, it is understood that each segment will have twomagnetic polarities (i.e., north and south) extending into and out ofthe page of FIG. 23. In most embodiments, the polarities of adjoiningsegments will be opposite, as shown in FIG. 25, however this need not bethe case. As shown in FIG. 25, one pole (e.g., north) is shaded, whilethe other pole (e.g., south) is not.

In some embodiments, the polygon is not a regular polygon. By varyingsegment length and miter angle it is possible to produce complex,asymmetric shapes, although a larger volume may be needed for theirdeployment, erection, and closure. Additionally, it is possible toinclude multiple “backbones” on either side of a magnetic segment,thereby allowing for even more varied shapes, such as adjoiningstructures with reverse curvatures.

In some embodiments, e.g. as shown in FIG. 23, high tenacity and hightensile modulus attachment points 22 are coupled to the device. In someembodiments, the attachment points 22 are twisted or braided fibers. Thefibers can be made from nitinol wire to assure that the attachmentpoints 22 deploy from the device once the device exits the deliveryinstrument. The attachment points 22 will allow a surgeon to grasp,secure, enclose and/or envelope the magnetic segments 10 to provide away to attach the flexible exoskeletal structure. The attachment points22 can also be used to place or remove the magnetic device, as neededduring the procedure.

Other features can be included in the magnetic device to provideattachment points 22. For example, holes can be placed in theexoskeleton and/or grooves placed in the magnetic segments to facilitateattaching and manipulating the magnetic devices. Furthermore, attachmentpoints 22, such as suture loops or other securement points, can servemany purposes. For example, they can allow a deployed and assembleddevice to be held in place, manipulated, or moved to an alternativelocation. In some instances, as described with respect to FIGS. 53-55,the attachment points allow the magnetic ring to be separated, removed,or redeployed. In other embodiments, attachment points can be used by aphysician to control the passage of the device(s) once an anastomosishas formed. For example, by attaching to an attachment point to tissueneighboring tissue the device is prevented from passing through ananatomical structure that may be of concern. In such embodiments, aseparate procedure (e.g., endoscopy) can be used to detach the devicefrom the neighboring tissue and remove the device(s).

Cross sections of the magnetic device are shown in FIGS. 23A and 23B.The cross section is taken at cut-line 23 in FIG. 23. As shown in FIG.23A, the magnetic segment 10 is surrounded on three sides by a channelformed from 0.001″-0.01″ thick, e.g., 0.001-0.008″ thick, preferably0.002″-0.004″ thick, more preferably 0.004″-0.006″ thick superelasticnickel titanium (shape metal), i.e., making up the exoskeleton 12. Thechannel comprises a flat peripheral band 14 that connects adjacentsegments 10, as well as lateral flanges 18 that effectively grasp theexterior of the mitered magnets that make up each segment 10. Theexterior edges 11 of the mitered magnets can be radiused or, morepreferably, chamfered to further improve clearance within the guidingchannel, and avoid catching operative devices (e.g., needles) on theinterior of the ring.

FIG. 23B depicts an alternative embodiment wherein the three-sidedchannel of 23A has been extended to include enveloping edges 24 thatmore completely couple the segments 10 to the exoskeletal structure 12.The edges 24 meet at a small gap 25 running the inside length of allsegments 10. In an embodiment, small amounts of adhesive are placed ingap 25 to secure the magnetic segment to the framework. In thisembodiment, the enveloping edges 24 provide robust physical protectionof the magnets, and prevent the magnets from being nicked or damaged,for example as the device is extruded from the delivery device. In FIGS.23A and 23 B, the magnetic dipole axis, 26, of each segment 10 has anorth and a south pole.

FIG. 24 shows the octagonal device of FIG. 23 in an open configurationwithin a guiding channel 27 as the device is extruded from the channel'sdistal end 28. Because the exoskeleton 12 is constructed from shapemetal, e.g., nitinol, the opened miter joints 15 and notch radius 16will immediately try to close as the device leaves the guiding channel27. The force of the shape metal is evident at both the proximal endmiter 29 and the distal end miter 30 which have partially closed totheir deployed configuration. In an embodiment, a central pusher 31within the guiding channel 27 is used to extrude the device while aretaining mechanism 32, optionally controlled with a slideable element33 reversibly engages the device's attachment point 22. For example, asuture loop passing through attachment point 22 and through a lumenwithin the central pusher 31 to its proximal end can be used to retainand control placement of the device.

Various embodiments of the two portions of the magnetic anastomosisdevice, i.e., the magnet assembly and the exoskeleton are shown in FIGS.26A-26C. On the right-hand side of FIG. 26A, a metastable assemblage ofeight magnetic segments is held together by magnetic attraction alone,while on the left, a single piece, shape set, three-sided nickeltitanium (nitinol) exoskeleton 12 is shown. The exoskeleton 12 has a gap13 located at the 10:00 position, allowing the exoskeleton to belinearized for deployment with a surgical device. This octagonal NiTiexoskeleton can be channel flared and octagon opened to increase thecross-sectional clearance, and will accept into its channel themetastable magnet assemblage on its right. The devices and methods usedto open the exoskeleton 12 and load the magnets are described below withrespect to FIGS. 31-33.

The placement of the exoskeleton over the magnetic assemblage determinesthe location of the gap 13, as described in greater detail in FIG. 26B.As shown in FIG. 26B, the gap in the exoskeleton can be placed such thatthe there is a north pole to the left of the gap and a south pole to theright of the gap, or vice versa. The location of the gap with respect tothe polarity of the magnets results in a “handedness” of the finisheddevice in that the two devices are now non-superimposable mirror images.(There is no “right” or “left” hand for the devices, and they could aseasily be termed “red” and “green”, provided that the consequence of theorientation is appreciated.) One benefit of producing devices withdifferent handedness is that when two devices of opposite handedness areassembled, it is impossible for the gaps to align. Because the gaps ofthe matched devices are not aligned, there is no risk that a coupled setof devices can re-open once properly deployed. Devices with handednessare not limited to octagonal dipole configurations, as other polygonalstructures will also exhibit the same properties.

The exoskeletons of the magnetic anastomosis devices of the inventionneed not be limited to one-piece construction. For example, a device maycomprise a plurality of pieces 12 a as shown in FIG. 26C, that areformed into a plurality of hinge structures. As shown in FIG. 26C, ametastable octagonal dipole assembly, i.e. shown in the center of FIG.26C, can be coupled with, e.g., seven exoskeletal segments, wherein eachexoskeleton will direct self-assembly of a single miter joint. For themost part, assembly of the device would proceed as described below, thatis, the exoskeleton would be opened in a cold metastable state, and thenthe exoskeleton would be placed over two or more magnetic segments. Theconstruction of the invention is not limited to the configurations shownin FIGS. 26A-C, however, as a magnetic anastomosis device may have,e.g., eight magnets and only two exoskeletal pieces. Additionally, theexoskeletal pieces do not have to be identically shaped.

Furthermore the exoskeleton or exoskeletal structure is not limited tocomplete encapsulation around the magnet segments or a structure thattraverses the entire magnetic assembly length. Rather, the exoskeletonincludes any external structure that acts on the outer surface of theplurality of magnet segments, stabilizing them, keeping them aligned inplane, and ensuring the magnetic assembly assumes its pre-determineddeployment shape upon deployment. For example, intermittently attachingshape memory hinges around each of the magnet miter joints could achievethe desired exoskeleton effect. A “U-channel” or even less surfacecoverage could still achieve pre-forming, articulation, and resistnon-planar bending. In some embodiments, the exoskeleton will pinch orgrasp the magnetic segments. In some embodiments, the exoskeleton willbe affixed to the magnetic segments, e.g., with glue or a wire orsuture. In some embodiments, the exoskeletons will be affixed to themagnetic segments with a physical coupling, e.g. a screw or rivet.

The stability of the mitered magnet configuration is further illustratedin FIG. 27. As shown in FIG. 27, a collection of only seven of theoctagonal segments creates a metastable geometric structure because ofthe alternating N/S construction with the poles oriented normal to theface of the trapezoids (i.e., out of the plane of the figure). As shownin FIG. 27, the magnetic attraction between adjacent mitered joints issufficient to keep the structure aligned and sufficient to overcome therepulsive forces of the two segments on either side of the opening. Ifone were to instead choose to keep the magnetization vector within thepolygonal plane, i.e., rotated 90° and running parallel to the plane ofthe polygon, the magnetization could not be optimally orthogonal to allthe segment ends in anything higher than a square. In other words, thestructure would only be stable with poles aligned up/down and left/righton the figure. However, with the dipoles oriented N/S into and out ofthe page (normal to all the trapezoidal faces) not only are thedevice-to-device attractive forces optimized, but the balanced magneticattraction between mitered segments stabilizes the magnet assembly.Additionally, the same segment-to-segment attraction provides theself-assembly forces that cause the device to properly curl into apolygon upon exiting the delivery device.

Details of construction of the shape metal exoskeleton are shown inFIGS. 28 and 30-32. FIG. 28 shows a photoetch pattern for a thin walledtubular structure that will be modified to form the exoskeleton of anoctagonal magnetic device, such as shown in FIG. 23. Using knownphotoetch techniques, the starting material, which may be anybiocompatible shape metal such as Nitinol, is etched to provide theneeded miter clearances 15 and notch radii 16 to allow the etched pieceto be shaped into an exoskeleton, as described below. The photoetchedmaterial may also include holes 56 as needed to attach fiber loops tocreate attachment points 22, described above. Alternatively, nitinolsheets can be cut into strips and then photoetched or stamped to createa pattern similar to FIG. 28. Alternatively, stacks of NiTi sheets canbe wire EDMed in an appropriate clamping fixture to produce a stack ofexoskeleton blanks with the required initial external shape. Holes canbe drilled in the resulting stack or in separate pieces by either EDM orlaser, respectively.

Starting from the photoetched or otherwise machined pattern of FIG. 28,the exoskeleton is formed by a sequence of fixtured shape settingsaccomplished most commonly by holding the part in the desired shape andbriefly heating to 900° F. (480° C.), most preferably in a bed ofchromatographic silica fluidized by either air, argon or nitrogen andheated by immersed resistance elements. Alternatively, shape setting canbe carried out in vacuo. The first step in the sequence is to shape anelongated ‘square’ channel (side flanges 90 degrees from backbone), thesecond to shape this linear square channel into a closed polygon, andthe third is to pinch the sides of this polygonal square channel inwardtoward the central polygonal plane. The final shape looks similar to asmall polygonal beveled picture frame (see FIG. 26A). If nitinol sheetis the starting material the angles of the flanges are folded to achievean angle less than 90 degrees so that the exoskeleton, after being‘cold-opened,’ as described below (see FIGS. 32A-33B), to angles ofapproximately 135 degrees and having the magnets placed, can, uponrewarming, properly pinch the magnetic assemblage. After machining andshape setting, the resulting exoskeleton 47 is sufficiently robust andhas a natural tendency to curl up into a polygonal structure, 12 asshown in FIG. 26A.

FIG. 29 shows the deformation of a thin-walled nickel titanium roundcylindrical tube 34 formed by a die 51 into a thin-walled square tube35. The cylindrical diameter is chosen such that the total circumferenceof the cylinder's neutral axis 49 has the same length as the analogousneutral axis 50 in the required square tube. Sharper corner radii can beachieved by this method than when ‘channel forming’ sheet material giventhe much smaller bending strain when measured from an already small tuberadius. Forming at elevated temperatures can also increase tolerablebending strain. In some embodiments, the bottom of the square tube canbe removed, e.g., with EDM, to produce a square channel. One advantageof a square channel is that it is not necessary to “unpinch” the shapemetal. A device of the invention can be formed by merely inserting themagnetic segments and then securing them to the exoskeleton withadhesive, e.g., cyanoacrylate glue.

In many instances, the channel of the exoskeleton will be shape set suchthat, at temperatures above its Austenite finish (A_(f)) temperature,the exoskeleton returns naturally to a pinched configuration with someamount of force (see FIG. 33A), which allows the exoskeleton to grab themagnetic segments, e.g., as detailed with respect to FIG. 23A.

Prior to placing the magnetic assemblage inside the exoskeleton, it isnecessary to open up the pinched channel. The shape metal exoskeleton iscooled whereupon it becomes very soft and deformable, said deformationbeing perfectly recoverable upon warming. While the requiredtemperatures will vary depending upon the particular alloy used, asufficient temperature to work the material is typically around −30° C.Opening the exoskeleton is accomplished using the device shown in FIGS.32A and 32B, described below, operated in a bath having a temperaturetypically less than about −30° C., e.g., less than −35° C., e.g., lessthan −40° C.

After the channel has been flared, the cold closed octagonal frame isremoved from the bath, and four of the eight segments are swung open,two on either side of the gap, so as to form a “C” shaped structureshown to the left of 31A. This still cold C shape can then receive themagnetic assemblage within itself, most preferably with the magneticassemblage on an octagonal mandrel that gives the assemblage moremechanical stability during manipulation. The two segments on eitherside of the gap, four in all, are then bent back into their initialclosed octagonal shape while they are still cold and their sides arestill open or flared and able to envelope the magnetic assemblage (rightside of FIG. 31A). After placing the octagonal exoskeleton over themagnetic assemblage, the exoskeleton is allowed to rewarm. Upon warmingthe exoskeleton above the metal A_(f) temperature, the channel returnsto its pinched shape, thereby clamping the magnets, and resulting in acomplete magnetic anastomosis device, as shown in FIG. 31B.

An opening tool 320 is shown in FIGS. 32A and 32B. The opening tool 320comprises a distal segment 322 and a proximal segment 324. The distalsegment 322 is attached to a shaft 327 that fits though a channel 328inside the stem 329 connected to the proximal segment 324. Both thedistal segment 322 and the proximal segment 324 comprise edges 323 and325, respectively, that interface with the channel of the exoskeleton,allowing it to be opened. In practice, the exoskeleton in a pinchedconfiguration is loaded onto the closed opening tool 320, as shown inFIG. 33A. A retaining mold (not shown) is placed over the exoskeleton onthe opening tool to assure that the exoskeleton does not jump off theopening device during the opening process. The retaining mold has atapered octagonal cavity such that downward force on the opening tool320 pushes the exoskeleton against the edges 323 and 325 to increase theeffectiveness of the opening procedure. Other methods of opening thechannel of the exoskeleton can include, for example using hydraulic orpneumatic pressure in a bladder placed in the channel to open the edgesof the exoskeleton to allow the exoskeleton to accept the magneticsegments.

At the next step the opening tool 320, in the closed position with theexoskeleton attached and the retaining mold over the exoskeleton, issubmerged in a bath of cold ethanol (−60° F.). While ethanol is thepreferred solution, it is also possible to use other biocompatiblefluids that will achieve the desired temperature, such as isopropanol.Once the exoskeleton is sufficiently cool (about 1 minute), the channelof the exoskeleton is opened with the opening device in the cold ethanolbath, to achieve an open channel, such as shown in FIG. 33B. The openingtool and exoskeleton are then removed from the bath, the open-channelexoskeleton removed from the opener, and then the open channelexoskeleton is returned to the cold ethanol bath until the magnetassemblage is ready for loading. While in the cold bath, the exoskeletonis in a metastable state and can even be removed from the bath for shortperiods of time before the shape metal will warm sufficiently to returnto its natural pinched condition.

Prior to assembly, the magnetic assemblage is also placed in the coldbath to cool. The magnetic assemblage typically only requires a fewminutes to cool sufficiently. Once the magnetic assemblage is cooled andready for the exoskeleton, the magnetic assemblage and the exoskeletonare removed from the cold bath, and the exoskeleton placed on themagnetic assemblage. See FIGS. 31A and 32B. Care must be taken to placethe gap in the correct position with respect to the north and southpoles to achieve the desired “handedness” as discussed below.Furthermore, the assembly process must be completed in about 30 seconds,otherwise the exoskeleton will return to its pinched configuration. Thecompleted magnetic anastomosis device is then allowed to warm to roomtemperature.

Once the completed magnet and exoskeleton assembly has warmed to roomtemperature, some amount of cyanoacrylate glue is applied to variouspoints along the assembly (center of segments) and allowed to be wickedbetween the exoskeleton and the magnetic segments. In some embodiments,the additional glue is not necessary because the assembly issufficiently robust. Once finished, the devices are sterilized andpackaged in the elongated configuration (see FIG. 51) in sterilepackaging for loading into a delivery device in the operating room.

A detailed view of coupling octagonal magnetic devices is shown in FIG.30. Essentially the two devices align so that the N face of each segmentof the bottom device aligns with a S face of each segment of the topdevice. One concern with this arrangement is that it is possible thatthe gap 37 of the exoskeleton of the top device could align with the gap38 of the exoskeleton of the bottom device, thereby allowing the coupledring to open at the aligned gaps 37 and 38. This coincidence can belessened by assuring that the exoskeletons and the magnet assemblies areconstructed to give a “handedness” to each device, i.e., the gap 37 isto the left or right of the first N segment when view from above, andthen assuring that one of each hand is deployed to create ananastomosis. This concept is explained above in greater detail withrespect to FIG. 26B. By only coupling devices with different handedness,the gaps will never be coincident in a coupled device because thatorientation (i.e., overlapping gaps) would be in full repulsion.Additionally, it is notable that a coupled device, i.e., as shown inFIG. 30, is remarkably non-magnetic when approached with anothermagnetic structure. Because all of the strong magnetic fields arecoupled between the two devices, the lines of magnetic flux mostly wraparound and reenter the coupled device elsewhere. By this design, coupledoctagons show almost no interaction with an external magnet. Of course,alternative device designs can be used to allow magnetic coupling tocoupled devices, e.g., to a shunt.

While a simple device can be constructed from a collection ofidentically-shaped magnets, it is also possible to constructself-assembling anastomosis devices containing unequal numbers of mitersor miters of different sizes and configurations. For example, FIG. 34shows a complex octagonal multipolar ring magnet comprising dipoles,quadrupoles and hexapoles with attractive forces at all miters. In thisdesign each miter is still magnetically attracted to the adjacentsegment helping the device to self-assemble. However because of theasymmetries in the design, from a distance the deployed ring has a widermagnetic signature and a tendency to align in only one configuration. Inother embodiments, the structure can be a square with 2 dipoles and 2quadrupoles, i.e. as shown in FIG. 35.

In the device of FIG. 35, the magnetic potential will drive azimuthalalignment of two matched rings into a unique and reliable orientation.In this configuration, the first 90 degrees of rotation takes a pair ofdevices from full attraction to zero. The second 90 degrees takes thepair from zero to full repulsion, and the third 90 degrees rotationtakes it back through a zero. Thus, the configuration of FIG. 35 allowsa user to confidently choose between assured coincidence of ring opening(if desired) and assured lack of coincidence (typically desired). Thisis a notable advantage over square design having identical dipoles, asshown in FIG. 36. The design of FIG. 35 is beneficial if one device iseasily visualized and oriented, e.g. because it is against the stomachwall, while the matching device is difficult to orient because it is inan inaccessible location, e.g., the bile duct. The confidence inorientation of the square design of FIG. 34 is not available in allpolygonal structures, however. For example, the orientation is notavailable to regular hexagons because each dipole-quadrupole pairreverses polarity and there must be an even number of suchdipole-quadrupole pairs for the ring to attract itself closed, i.e., inorder for the ends to have opposite polarity across the opening.Nonetheless, the square design of FIG. 35, with small changes in miterangles and segment length, can clearly morph into an irregular hexagonwith alternating simple dipole segments such as, for example, shown inFIG. 44.

As is clear from the previous example, irregular geometry and segmentsize can contribute greatly to azimuthal control. Nonetheless, elongatedsegments can make it difficult to deploy the device through a curvedchannel (e.g., the contours of an endoscope), and the elongated segmentscan complicate self-assembly at the deployment site.

By using potential energy diagrams, it is easy to identify theorientations available with a device of the invention. For example, FIG.37 and FIG. 46 show magnetic potential energy curves of two matingpolygons as a function of their relative azimuthal angle of rotation.FIG. 37 (1) shows that the square design of FIG. 35 couples in only oneorientation at 0 degrees. FIG. 37 (2) shows that the square design ofFIG. 36 is equally comfortable at both 0 and 180 degrees, thus it isequally likely that the two devices will be aligned or anti-aligned.Similarly, FIG. 37 (3) shows the potential energy profile of a regularhexagon only comprising dipole segments. In the instance of (3), it isactually more likely than not that the two devices will not be correctlyaligned if the two devices are merely placed in proximity.

Nonetheless, it is not difficult to use the methods of construction toproduce more elaborate structures, such as the structure correspondingto FIG. 37 (4), i.e., the structure of FIG. 34 having dipole,quadrupole, and hexapole segments. Like the structure of FIG. 37 (1),the structure corresponding to FIG. 37 (4) can only be coupled in oneconfiguration. More irregular shapes will give rise to highly erraticenergy states, such as shown in FIG. 46, corresponding to the octagonstructure of FIG. 45, having very short transitions in the hexapolesegment. Regarding the octagonal embodiment of FIG. 34, it is clear thathigher order polygon devices can be constructed having only a singleorientation of interlock with a mating device. Such arrangements assurethat the gaps of the two devices are not aligned in the final assembly,and additionally allow orientation of peripheral devices, such asshunts. As shown in FIG. 37 (4), the eight different states this systemcan occupy include states with intermediate energy levels whichrepresent energy wells between which the system could move. However,with small amounts of manipulation, the paired devices will tend to fallinto the lowest given potential energy configuration.

In some embodiments, it may be beneficial to use a multi-pieceexoskeleton to fabricate a magnetic anastomosis device. When preparinglarger anastomoses requiring larger structures, it may be easier todeliver two or three separate pieces per polygon because the entirepolygon cannot be negotiated through the delivery device in an uncurledstate, similar to FIG. 24. FIG. 38 shows a photoetch pattern for a0.004″ nitinol sheet that is shape-set for use as a portion of theexternal exoskeletal structure for the magnetic ring of FIG. 41. In thedesign of FIG. 38, short flanges 18′ are half as wide as regular flanges18, allowing two exoskeletal structures to share a single magneticsegment when assembled. FIG. 39 shows FIG. 38 after channel shapesetting the patterned nitinol sheet for several minutes at 900° F. (480°C.). In alternative embodiments, the patterned nitinol may be formedwith laser cutting or stamping.

FIG. 40 shows a magnet assembly 44, comprising two symmetric quadrupolarsides 42 and four dipolar segments 43 ready for adhesive assembly withtwo external 44 and two internal 45 exoskeletal structures. Alternativedesigns may use asymmetric exoskeleton components to assure that adevice self-assembles in a particular way or with one portion foldingbefore the other portion. See, e.g., FIG. 26C. FIG. 41 shows a varietyof external and internal exoskeletal structures depicting magnetizationthrough the trapezoidal faces of each segment, normal to the polygonalplane.

In some embodiments, a self-assembling device can have a living hingethat allows the device to be deployed in a folded arrangement, e.g., asshown in FIG. 42. FIG. 42 shows the extrusion of the hexagonal structureof FIG. 41 from a rigid rectangular channel 46. Though segments 47 and48 repel each other in the channel, there is a strong magnetic force onsegment 47 to move upward, out of the paper, and on segment 48 to movedownward into the paper and attract at their bottom and top surfacesrespectively. As shown in FIG. 43, it is possible to roughly calculatethe distortions that result in the exoskeletal structure in the regionsbetween polygonal segments during deployment, i.e., during the changefrom stowed to deployed configuration. The formulas for calculatingstrain as a function of angular excursion, material thickness andintersegmental “free length,” (L₁) are well known. Based upon thesecalculations, it can be determined ahead of time whether a particularconfiguration of self-assembling magnetic device is likely to survivedeployment from an endoscope, for example.

As shown in FIG. 47, an octagonal device can be constructed bysequentially deploying four separate pieces, each consisting of twolinked segments, mutually attracted to each other. As shown in FIG. 47,each segment has at least one attachment point (loop) of high-tenacitymaterial for manipulation. These loops can be simple suture loopsemerging through holes in the exoskeletal structure, e.g., as describedabove with respect to FIGS. 23 and 28. Alternatively, the loops can beexternal manifestations of high tenacity strands running betweenmagnetic segments and providing tensile reinforcement to the exoskeletalstructure against tearing at the intersegmental regions 19, as shown inFIG. 48. In embodiments having the tensile reinforcement, a crosssection of the exoskeleton may have regular guide loops (elements 20 and21 of FIGS. 23A and 23B) to maintain the tensile members in place. Thereinforcing elements can be solid, stranded, twisted or braided and canbe comprise stainless steel, titanium, aramid fibers, orientedpolyesters of various chemistries, gel-spun UHMW polyethylene (Dyneema™,Spectra™) or superelastic (37C) nickel titanium wires. Loops therein canbe created with knots, braid splicing, brazing, welding, or adhesivebonding. In some embodiments, the attachment points (e.g., loops 55)emerging through holes 56 photoetched through the patterned shape metal14 prior to shape setting. See the discussion with respect to FIG. 28.The attachment points can be engaged by retaining means such as suturesor staples, as needed during the procedure. The attachment points canalso be manipulated, e.g., with forceps or a robotic grabber duringdeployment.

As a further exemplary embodiment, FIG. 48 shows an isometric view oftwo different “two-segment” designs. Depending upon the miter, acollection of such two-segment designs can form a regular hexagon or aregular octagon. The top embodiment of FIG. 48 depicts a versioncomprising a loop of nickel titanium wire, between 0.003″ and 0.010″diameter, preferably 0.004-0.006″ diameter. The loop emerges throughopenings in the back of the exoskeleton and runs in grooves, 20, in theouter surface of the magnetic segments to the other end loop or otherfixation means, thereby providing additional strength and integrity tothe exoskeletal structure. The bottom embodiment of FIG. 48 shows analternative construction comprising two attachment points 55 (i.e.,suture loops) on the ends of a suture length 56 that runs along thespine of the two-segment piece. In the bottom embodiment of FIG. 48, twoknots 57 are trapped within a depression in the magnetic segment 58,allowing the exoskeleton to sit flush against the magnetic segment 58.In either of these embodiments adhesive can be wicked into these holes,and/or other holes elsewhere in the exoskeleton, to achieve magnetsegment immobilization.

In alternative embodiments, the magnetic segments can be connected witha resilient hinged material. For example, a central exoskeletal band canbe achieved with either pseudoelastic materials or fiber reinforcedcomposite structures or a combination of both. In some embodiments thehinges can be formed from Dyneema®, Spectra®, Vectran®, Kevlar® orsimilar materials. These fibers have especially high-tensile moduli, andcan be fabricated to provide the tensile integrity andout-of-polygonal-plane stiffness similar to the parallel flatexoskeletal members, described above. In an embodiment, multiple tensilefibers are bonded to the backbone and sides of the magnetic segments,thereby maximizing the out-of-polygonal-plane stiffness and reinforcingthe miter joint. In other embodiments, the magnetic devices can comprisea combination of shape metals and tensile fibers. In some embodiments,the structure could include a nitinol exoskeleton and nitinol wirereinforcement, e.g., 0.002″-0.010″, preferably 0.004-0.006,″ diameter.As discussed previously, the nitinol wire can also be used to createattachment points along the structure.

In some embodiments, the exoskeletal structures are coated with abiocompatible coating. This coating could be applied in a variety ofways, including plating, vapor deposition, dipping, or spraying. In anembodiment, the coating is polytetrafluoroethylene (PTFE), a.k.a.Teflon. In some embodiments, the exoskeletal structures are gold,silver, or platinum plated. In some embodiments the exoskeleton iscoated prior to assembly with the magnetic segments. in otherembodiments, the exoskeleton is coated after the exoskeleton has beenmated with the magnetic assemblage. It is also possible to coat thestructures with a drug-eluting coating, such as Parylene™, that can beused to deliver drugs in a localized and controlled fashion. Drugssuitable for elusion include anti-angiogenic and anti-clotting coatingsthat discourage the attachment of tissues to the magnetic devices.

A device of the invention may also include features or protrusions, asnecessary. Such elements can be incorporated into the structures toincrease pressure at certain contact points by reducing contact area. Insome instances, protrusions will assist in placement and retention of acoupled device. Other features may include a raised channel or radiusformed into the exoskeletal frame prior to assembly. In someembodiments, a raised feature on one magnetic device is matched with achannel on the mating magnetic device. A magnetic anastomosis devicehaving a raised feature is shown in FIG. 49.

In addition to features that assist with placement and retention of thestructures, other features can be added to assist with detachment andpassage of coupled devices. As discussed above, when an anastomosis hassufficiently formed, and the surrounding tissue has necrosed, thecoupling of magnetic devices will fall away from the tissue and passnaturally through the body. Preferably the used structures will passposteriorly, in the direction of normal peristaltic motion, thusensuring proper passage. In other embodiments, it is desirable to directthe coupled devices move toward a larger lumen (e.g., the smallintestine) as the coupled devices disengage the tissue. Various designfeatures can be added to ensure the direction of exoskeletal structurepassage. For example, FIGS. 50A and 50B show a preferred embodiment,where the device on the preferred side of passage is slightly larger insize than the mating device. This additional material (indicated by thedotted lines) provides enough resistance that the devices will pass intothis preferred lumen, and not pass through to the unintended lumen.Additionally, by introducing additional material attached to magnets,the same effect can be achieved, in situations where no additional sizeor lumen delivery space is available.

In another embodiment, portions of the exoskeleton can modified tofacilitate planned or emergency disassembly of the device. For example,biodegradable components can be incorporated into the exoskeleton toassist in self-removal after anastomosis formation. PLA, PLGA, or PVA,or copolymers comprising these polymers, can be included to encouragethe structure to break down over time and pass naturally in small,atraumatic segments. In other embodiments, the exoskeleton will befabricated with a “ripcord” or other structure that can be cut ordetached with an endoscopic or laparoscopic instrument, thereby causingthe assembled device to fall into several pieces that can be passedharmlessly through the body.

Packaging and introducer tools are also important in facilitating easyand effective placement of self-assembling magnetic devices. Withoutproper packaging and introduction into the delivery device, the magneticdevice may become damaged and take on an unintended configuration upondeployment. Prior to loading into a delivery device, the exoskeletalstructure is packaged in a sterile containment tube, which prevents theexoskeletal structure from opening and self-assembling. This containmenttube also facilitates easy introduction into the endoscope or catheterdelivery system with external dimensions compatible with the proximalport to which it is being introduced. FIG. 51A shows a containment tubewith an exoskeletal structure pre-loaded. FIG. 51B shows the exoskeletalstructure being pushed into the channel using a deployment rod. Thedetails of the deployment rod are shown in FIG. 52.

In one embodiment, octagon magnetic devices are stored and shipped in anapproximately 6 inch polyethylene tube with caps on each end. Theinsertion end (the end that is eventually loaded into the scope channelor proximal scope connector) has a cap that is removed immediately priorto insertion into the scope. The end of the tube may be tapered as shownin FIG. 51A. The proximal end of the insertion tube has a cap with ahole drilled in it to accommodate a Teflon rod. The rod may be shaped asshown in FIG. 52. When loading the octagon, the Teflon rod is advancedinto the insertion tube, thereby pushing the octagon outside of the tubeand into the endoscope, as shown in FIG. 51B. The insertion tube andadvancement rod allows for a convenient and sterile method for octagoninsertion into the endoscope.

In some embodiments, the magnetic devices are stored and shipped in afinal assembled state, i.e., as completed polygons. Because thisconfiguration is lower energy, it provides a longer shelf life, e.g.,because the exoskeleton are not be strained over long periods of time.This strain could also weaken adhesive (if used). The lower energyconfiguration will also be more robust during shipping, especially whenthe devices may be accidentally exposed to cold temperatures, such as inthe cargo hold of a plane. If an extended device having a shape metalexoskeleton were exposed to sufficient cold, the shape metal couldbecome pliable enough that the magnetic segments will come loose or movetoward one another and cause imperfections in the exoskeleton.

In some embodiments, multiple exoskeletal structures can be loaded intothe endoscope or delivery device. Loading multiple structures canpotentially simplify and shorten the procedure due to reduced exchanges,complexities, and intubations. For example, as discussed with respect toFIG. 4B, a first device can be placed endoscopically within the GItract, and then the second device can be placed at a different locationwithin the GI tract using the same endoscope. Additionally, pairedmagnetic devices can be loaded into a single tube such that a matchedset, or set having the desired handedness are deployed.

In some embodiments, a deployment tool is required to push a magneticdevice out from the deployment lumen, e.g., an endoscope channel. Oneembodiment of a deployment tool is shown in FIG. 52A. The deployment rodshould be incompressible so as to provide adequate pushability against adevice within a delivery lumen, e.g., and endoscope delivery channel. Itshould also be flexible and lubricious, so that the deployment tool iseasily advanced through the endoscope channel after the endoscope hasbeen moved to the site of the anastomosis. The deployment toolpreferably has a rigid distal tip, either magnetic or non-magnetic. Insome embodiments, the deployment tool comprises a magnetic (preferablyneodymium) tip that helps to deploy a magnetic anastomosis device andhelps to guide the distal end of the device to avoid pinching tissue(see FIG. 52B). Furthermore a magnetic tip allows the deployed magneticdevice to be easily manipulated with the deployment tool. In otherembodiments, a non-magnetic distal tip (stainless steel or similar)allows the deployment rod to manipulate the magnetic device withoutbecoming inadvertently attached to the device.

Once deployed, magnetic anastomosis devices can be precisely deliveredto the appropriate anatomical location using the deployment tool. Insome embodiments, this will be accomplished with a deployment toolproviding additional degrees of freedom, specifically axial displacementand rotation, about the scope axis. As described above, the distal tipof the deployment tool may be magnetic or ferromagnetic, to providecontrol of the magnetic device before, during, and after deployment. Insome embodiments, the deployment tool tip is shaped with a miter thatmatches the magnetic device's proximal end, to maximize surface area andmagnetic attraction, as shown in FIG. 52B. This tip profile also helpsto prevent tissue from getting caught as the magnetic ring closes,because the deployment rod covers the proximal ring surface andgracefully hands the space off to the awaiting distal end of themagnetic ring, waiting to close off and complete the magnetic ringformation. To release the deployed ring from the deployment tool, thedeployment tool is simply withdrawn, or the endoscope advanced, untilthe delivery tool pulls into the endoscopes working channel and theendoscope tip pushes on, and releases, the magnetic ring. In someprocedures the deployment tool may be redeployed after it has beendecoupled from the magnetic device, for example to manipulate a deployedmagnetic device into the proper location. Alternatively, the deploymentdevice can be used to locate a magnetic structure that has been place onthe other side of a tissue plane, but is not visible through theendoscope.

In some embodiments, the distal tip of this deployment rod will have aheavily radiused opening that allows suture materials to pass through,e.g., as shown in FIG. 52A. The channel will typically run the length ofthe deployment rod. The channel can be used, for example to allow hightensile sutures to be accessed at the proximal end of the endoscope, asdiscussed in detail below with respect to FIGS. 53 and 54. In someembodiments, the deployment rod may comprise a radiopaque or echogenicmarker to facilitate location with fluoroscopy or ultrasound,respectively.

In some embodiments, a target marker can be delivered and anchored to aprecise location in the organ, structure, or lumen, where theexoskeletal structure is to be delivered. Preferably this target markercan be easily identified through endoscopic visualization, fluoroscopy,and ultrasound. Ideally this target can also be used to guide thedeployed exoskeletal structure precisely into place.

Additionally, it may be necessary in some procedures to control bodilystructures and/or tissues so that the device can be deployed andsuccessfully self-assembled. That is, prior to device deployment, aregion should be identified with a sufficient landing zone andsufficient deployment space. If tissue or bodily appendages come inbetween a structure that has not completed self-assembled, the assemblymay not adequately close and properly form. In such instances, it ishelpful to have a delivery device that provides isolation from apotentially challenging environment where the self-assembling device mayotherwise have trouble closing. In an embodiment, a balloon can be usedto provide the needed isolation, thus providing control over anotherwise challenging environment.

An external structure embodiment that allows for significantmaneuverability and delivery of the exoskeletal structures to preciselocations is shown in FIGS. 53 and 54. As shown in FIG. 53, two hightensile sutures members are attached and integrated into the exoskeletalstructure. The two tensile members are attached to the device at points180 degrees apart. Each suture then runs through the tip of thedeployment rod, through the deployment rod length, and is accessible atthe proximal end of the endoscope. The tensile members can be attachedto a handle or tension wheel on the proximal end, to simplify placementof the deployed device. For example, pulling on both sutures will allowa surgeon to center the deployed device. The device can also be movedleft/right and rotated by manipulating the tensile members. Also, whenthe magnetic frame is deployed through a needle or catheter into adifferent organ, structure, or lumen, these integrated sutures providethe ability to pull back and assist in magnetic frame capture betweentwo different and separated anatomical structures.

As appreciated by those of skill in the art, device placement isespecially critical in certain applications, such as creation of agallbladder anastomosis. In this situation, it is critical that thecaptured magnetic assembles encompass the puncture site, to ensure thearea is sealed and not leaking. To ensure that the device is deliveredapproximately on center of the puncture site, the tensile members can beused to pull the device back and center the device to assure that thepuncture site is sealed. Once the exoskeletal structure is deployed atthe desired target location, the sutures can be cut.

Additionally, should an exoskeletal structure need to be removed, one ormore graspers can be introduced (endoscopically or otherwise), allowingthe two tensile members to be used to provide an opening force as shownin FIG. 54. As shown in FIG. 54, the lateral force created by pulling onone or more attachment points causes a reorientation of the magneticsegments with respect to each other, thereby causing the ring to openup. For example, one of the sutures can be pulled through the deploymenttube while the other is pulled through a grasper, thus providing theneeded opposing force. In this instance, the deployment tube can bepulled back into the endoscopic channel, thereby pulling theun-self-assembled device back into the deployment channel.

As described above, the attachment points can be used to open a deployedand coupled magnetic anastomosis device. Because of the intense localforces required to decouple the paired magnets, the attachment pointsmay be looped around the magnetic segments as shown in FIG. 55. As shownin FIG. 55, a channel has been cut into the magnetic segment at theproximal end of the device (distal end would look identical). Thechannel can be cut with, for example, a wire EDM device. The channelassures that a high-strength suture loop (e.g., Dyneema™ or Spectra™)does not move from the magnetic segment once it has been placed. Thechannel also assures that the force is against the magnetic segment anddoes not cause the end of the exoskeleton to pull free of the magneticsegment. In the design shown in FIG. 55, holes are also provided in theexoskeleton to allow passage of the suture. Other designs are alsopossible, for example running the suture around the exterior of theexoskeleton. In some embodiments, the suture will be knotted to form aloop, e.g., as shown in FIG. 23.

An alternative technique for separating a deployed magnetic deviceinvolves a spreading tool. The tool engages the inner surface of thering formed by the magnetic segments. The tool can have a small amountof magnet attraction to facilitate seating on the ring magnet's innersurface. Once in place, the spreading tool expands in diameter, causingthe magnetic ring to open. Once opened, securement points on themagnetic ring can be engaged, allowing the opened ring magnet to bepulled back into the endoscope channel or retrieved by a retrievalbasket.

Additional devices and procedures are discussed below. FIG. 56 is aschematic illustration of the gallbladder, showing a parent magnet onone side of the organ wall and a daughter magnet, made of a paramagneticor ferromagnetic material, on the other side of the organ wall. In theillustrated scenario, the parent magnet resides on or is secured to thestomach wall (not shown in FIG. 56). Once installed, the parent magnetand daughter magnet are left in place, with the magnetic attractiveforces between them compressing the organ wall or walls, until anopening or anastomosis is created.

The parent magnet may, for example, comprise a permanent magnet such asa rare-earth disc or ring magnet (e.g., neodymium-boron-iron (NdBFe) orsamarium-cobalt (SmCo) attached to a means of mucosal or tissuefixation, such as an endoscopic clip (Olympus QuickClip 2 HemostaticClip device, Olympus Corporation, Tokyo, Japan), via a connection, suchas suture. In some embodiments, the parent magnet is large enough and ofa shape appropriate to create an opening of a size and shape sufficientfor an endoscope, catheter, or other surgical instrument to passthrough. For example, in the embodiment of FIG. 56, the parent magnet isin the form of a disc with a diameter between 0.5 cm to 6 cm, but with apreferable diameter of 1 cm to 3 cm. This range of diametric sizescreates an anastomosis large enough to avoid stricture formation thatmay prohibit endoscopic access.

One advantage of systems, methods, and kits according to embodiments ofthe invention is that the parent magnet and the daughter magnet need notbe of the same shape, size, or characteristics. For example, the parentmagnet may be relatively larger and adapted for delivery using one typeor size of instrument, while the daughter magnet or magnets may be of adifferent form and adapted for delivery using a different type ofinstrument.

The one or more daughter magnets or magnetic materials can include aplurality of paramagnetic or ferromagnetic steel ball-bearings or discshaving a sufficient size and/or shape for delivery by syringe using airor water pressure through an endoscopic biliary catheter, or a fineneedle aspiration needle. For example, the bearings or discs may smallenough to be deployed endoluminally via the cystic duct or can beendoscopically injected directly into the gallbladder from an adjacentorgan (e.g., the stomach) with the aid of endoscopic ultrasound (EUS)techniques, such as, for example, Endoscopic Ultrasound, Fine NeedleAspiration (EUS FNA). This technique differs from a conventionalcholecystogastrostomy using T-tags because the fistula is created bymeans of magnetic anastomosis rather than endoscopic suturing. In analternative embodiment, the one or more daughter magnets or magneticmaterials can include a magnetic slurry or paste.

The parent and daughter magnets or magnetic materials would generally bemade of a biocompatible material or coated with a biocompatible coating,such as Parylene (Specialty Coating Services (SCS), Indianapolis, Ind.)or other biocompatible coating materials, known to persons skilled inthe art.

The drawings depicted in FIGS. 57A-57E are views illustrating byexample, the deployment and retrieval of parent and daughter magnets tocreate an anastomosis between the gallbladder and the stomach.Specifically, FIGS. 57A and 57B show deployment of paramagnetic steelball-bearings into the gallbladder via a biliary catheter. FIG. 57Cshows deployment of a NdBFe parent magnet which is endoscopicallyclipped to the stomach wall. Capture of the bearings, shown in FIGS. 57Dand 57E, by the parent magnet, results in apposition of the daughter andparent magnets for the anastomosis.

In another embodiment of the invention, the daughter magnet or magneticmaterial, which may be used as the intra-gallbladder component in astomach-gallbladder anastomosis, comprises a second rare-earth magnetthat can be delivered by syringe using air or water pressure through anendoscopic biliary catheter or endoscopically injected into thegallbladder from an adjacent organ (e.g., the stomach) with the aid ofEUS FNA methodologies. Since the size of any one daughter element islimited by the cystic duct diameter, this embodiment may utilize a“self-assembling” structure for the magnetic elements, such that afterdeployment into the gallbladder, the daughter magnet's elements combineto form a larger structure, thus creating sufficient force between theparent and daughter magnets to result in anastomosis. This type ofmagnetic self-assembly is schematically illustrated in FIGS. 58A-58D, inwhich a train of daughter magnet components are injected into thegallbladder.

The components each carry two miniature magnets of variable magneticpolarity (e.g., north (N) or south (S)). In the case of quadrapolarmagnets, three magnet component combinations are possible: (i) N-N, (ii)S-S and (iii) N-S (which is equivalent to S-N upon rotation by 180° forsymmetric components). The daughter magnet components are small enoughto fit through the inner diameter of the biliary catheter or EUS FNAdevice or FNA needle. Careful selection of the injection sequence canyield a larger planar surface upon self-assembly within the gallbladderthan would be possible with any single component. The large daughtermagnet in FIG. 58D is assembled by means of the following magnetcomponent sequence (leftmost polarity first): N-S, NN, N-S, N-N, FIGS.58A-58D represent the simplest example of magnetic self-assembly, and amuch larger number of daughter magnet components can be used in practiceto provide sufficient mating area with the parent magnet in the smallintestine or stomach wall for effective anastomosis.

The simplest embodiment of a self-assembling magnet results from adipolar train of free (i.e. unconnected) rectangular or cylindricalmagnets extruded into space where the direction of magnetic polarizationis perpendicular to the direction of extrusion and the magnetizationdirection increases in consecutive components by 90° with each. For fourrectangular components, where the direction of magnetization ofconsecutive components is 0°, 90°, 180° and 270° in the planeperpendicular to extrusion, the resultant assembly will be a four-sidedrectangle (or a square in the case of identical components), as shown inFIG. 59. If this first magnetic train comprises the daughter magnet anda second, identical magnetic assembly comprises the parent magnet thenmating occurs when the two opposing pole faces (i.e., north and south inthe case of FIG. 59) come into proximity and the magnetic attractiveforces between the two assemblies cause compressive attraction betweenthe parent and daughter magnets. This compressive attraction which actsto compress the intervening gastric and gall bladder walls istheoretically sufficient to produce a leak-free magnetic anastomosiswithin a period of three to five days. The resultant window of access isaccessed by means of needle-knife incision or similar endoscopiccautery, known to persons skilled in the art.

FIG. 59 shows the arrangement for self-alignment between assembledparent and daughter magnets, using purely north/south attractive magnetmating. This configuration is suitable for generating significantcompressive force sufficient for the creation of magnetic anastomosisusing NdFeB magnetic components. However, to avoid repulsion between theparent and daughter assemblies, the opposing faces (i.e., north/south)need to be in closest contact.

FIG. 60 shows the arrangement for self-alignment between assembledparent and daughter magnets, using what we term “east/west” attractivemagnetic forces. This attraction takes advantage of the necessity formagnetic flux lines to form closed paths leading to a strong compressiveforce between the parent and daughter assemblies. While necessarily lessthan the compressive force for purely N/S attraction, this configurationmay also be suitable for generating significant compressive forcesufficient for the creation of magnetic anastomosis using NdFeB magneticcomponents when the separation distance is small (<1 mm) and high grademagnetic components (e.g., N50 or higher) are employed. The advantage ofthis configuration is that compression occurs independent of which facesare in contact and self-alignment is again achieved,

FIG. 61 illustrates the concept of “Magnet Self Assembly” in a connectedtrain of magnetic components. When a combination of quadruple and dipolecomponents are employed, a repulsive magnetic force can be used toensure self-assembly. As shown in FIG. 61, the self-assembly is due tothe repulsive forces associated with neighboring S poles (indicated bythe solid circles) in the upper two components and the neighboring Npoles (indicated by the crosses) in the lower two components which,together, drive the assembly into the final four-sided window.

In an alternate embodiment of the present invention, theintra-gallbladder daughter material may comprise a (super)paramagneticfluid consisting of iron-oxide particles or a suspension of ironfilings. In the presence of the parent magnet, the (super)paramagneticfluid would be strongly attracted to the parent magnet again, resultingin anastomosis due to the pressure between the two surfaces.

When external magnets are applied to the ferromagnetic daughter materialthey can be permanently magnetized to enhance the force of attractionbetween the parent magnet and the daughter material.

In the case of a stomach-gallbladder anastomosis, the parent magnet maybe placed on the lumen of the small intestine or on the stomach wallusing an endoscope that is introduced per-orally. The parent magnet maybe fixed to the mucosa of the small intestine or stomach using anendoscopic clip.

One method for deploying the daughter magnet or magnetic material wouldinvolve using the standard Endoscopic RetrogradeCholangiopancreatography (ERCP) technique and fluoroscopy, in which abiliary catheter is introduced over a guidewire into the gallbladder.The ball-bearings or other daughter magnetic material would be deliveredto the gallbladder through the biliary catheter using air pressure orliquid pressure provided by syringe. Alternatively, the daughter magnetor magnetic material may be deployed by direct injection from anadjacent organ into the gallbladder with the aid of EUS FNA typesystems.

As previously stated, the magnets may be delivered from one organ (e.g.,the stomach) into another adjacent organ (e.g., the gallbladder) via aFine Needle Aspiration (FNS) needle as illustrated in FIGS. 62 and 63.In this alternate embodiment, the individual magnets are circular innature and pre-assembled in a N-S arrangement and injected through theinner lumen of the needle under endoscopic ultrasound guidance. Thesemagnets may also be polarized in a N-S arrangement around thecircumference of the magnet to provide for a means of apposition withthe parent magnet once positioned. The distal and proximal magnets arepre-loaded with a suture through the distal and proximal eyelets of thedistal and proximal magnet elements respectively. Once injected throughthe needle or biliary catheter, the distal and proximal magnet elementsare secured together by tying off the pre-attached suture. As shown inFIG. 64, the suture is connected at the distal end to the deployedmagnetic daughter assembly and runs antegrade through the inner lumen ofthe aspiration needle or biliary catheter. Once the needle is retractedthrough the wall of the stomach, the suture remains connected at theproximal end to the parent magnet assembly as shown in FIGS. 64 and 65.Once the parent magnet has been deployed into the stomach or otherorgan, both daughter and parent magnets are pushed together to great atissue apposition between gallbladder and stomach as shown in FIG. 66.

Once deployed, magnet fixation is then achieved using EUS-guided T-tagdelivery through the gallbladder wall with a second attachment to parentmagnet in the stomach or small intestine, ensuring lock-in of parentmagnet to the daughter. Such a T-tag procedure is well known to personsskilled in the art of therapeutic endoscopy. Using fluoroscopicguidance, magnetic attraction between the parent magnet and theintra-gallbladder ball-bearings can then be confirmed.

When the parent and daughter magnets are left in place for a period oftime, the compressive forces on the tissue between the two magnetscauses the tissue to necrose, leaving an opening surrounded by afibrotic or collagenous border. After a period of several days (3-15),the creation of an opening, such as a cholecystogastrostomy, can beconfirmed by upper endoscopy or another such technique. At that time,the cholecystogastrostomy can be traversed using the upper endoscope forthe purpose of mucosal ablation. Mucosal ablation may be achieved usingargon plasma coagulation (APC), electrocautery, laser, or instillationof sclerosant (e.g. alcohol or ethanolamine or sodium morrhuate). Aprophylactic biliary stent may optionally be placed by endoscopicretrograde cholangiopancreatography (ERCP) prior to Gallbladder mucosalablation.

The purpose of gallbladder ablation is to induce scarring down of thegallbladder (i.e. functional cholecystectomy). This can be confirmedwith a follow-up endoscopy or by radiographic (e.g. oral contrast study)or nuclear medicine study (e.g. biliary scintigraphy or HIDA study).

Aspects of the invention relate to a surgical kit or kits that containall the additional, specialized surgical tools used to perform the tasksdescribed above. For example, surgical kits of the invention at leastinclude a parent magnet as described herein, and one or more daughtermagnets as described herein, loaded into an introduction device such asa biliary catheter or an endoscopic instrument (e.g., EUS FNA needleand/or system). In one embodiment, the kit(s) of the invention include,but are not be limited to, (i) the parent magnet in a suitablebiocompatible enclosure (e.g., Parylene or biocompatible plastic) and(ii) the daughter magnet material, preloaded for deployment. Optionally,the kit(s) of the invention include a grasping snare or pinchers forassisting with the introduction and placement of the parent and/ordaughter magnets.

For embodiments or situations in which the daughter magnet or magneticmaterial is injected directly into the gallbladder (either bytransgastric means or via the small intestine wall), the daughtermagnetic material may be preloaded in an EUS FNA injection needle withan outer diameter in the range of 10 Gauge to 25 Gauge, but morepreferably in the range of 15 Gauge to 20 Gauge. Deployment of bothmagnets into the gallbladder and/or stomach can be achieved with the aidof EUS FNA is this instance.

It should be noted that the present invention is not limited to theclinical applications listed in the afore-described disclosure. Thetechnology as per the disclosed description may also be utilized toachieve an anastomosis between other adjacent organs in both the upperand lower gastrointestinal tracts such as, but not limited to, betweenthe small intestine/gallbladder, the stomach/duodenum and theileum/colon for bariatric/metabolic purposes. The daughter and parentmagnet components may be delivered during simultaneous endoscopy andcolonoscopy procedures and mated under fluoroscopy. The afore-mentionedendoscopy and colonoscopy procedures are well known to persons skilledin the art of therapeutic endoscopy.

While the invention has been described with respect to certainembodiments, the embodiments are intended to be exemplary, rather thanlimiting. Modifications and changes may be made within the scope of theappended claims.

INCORPORATION BY REFERENCE

References and citations to other documents, such as patents, patentapplications, patent publications, journals, books, papers, webcontents, have been made throughout this disclosure. All such documentsare hereby incorporated herein by reference in their entirety for allpurposes.

EQUIVALENTS

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The foregoingembodiments are therefore to be considered in all respects illustrativerather than limiting on the invention described herein. Scope of theinvention is thus indicated by the appended claims rather than by theforegoing description, and all changes which come within the meaning andrange of equivalency of the claims are therefore intended to be embracedtherein.

The invention claimed is:
 1. An implantable device comprising: a plurality of magnetic segments; and an exoskeleton that covers exterior portions of the magnetic segments and couples the plurality of magnetic segments to one another, wherein the exoskeleton comprises a deformable material configured to return to a default shape from one or more deformed shapes, wherein, when in the default shape, the exoskeleton is adapted to position and maintain alignment of the plurality of magnetic segments relative to one another to thereby direct the plurality of magnetic segments to self-assemble into a geometric shape based, at least in part, on magnetic attractive forces between adjacent magnetic segments.
 2. The implantable device of claim 1, wherein the exoskeleton covers a portion of the exterior of at least two of the magnetic segments.
 3. The implantable device of claim 2, wherein the exoskeleton is deformable to allow the magnetic segments to be aligned linearly.
 4. The implantable device of claim 1, wherein the exoskeleton comprises a shape memory material.
 5. The implantable device of claim 4, wherein the shape memory material comprises a metal alloy comprising a nickel alloy, a copper alloy, a zinc alloy, a platinum alloy, or a cobalt alloy.
 6. The implantable device of claim 1, wherein the device comprises four or more magnetic segments and the device self-assembles into a polygon.
 7. The implantable device of claim 6, wherein the polygon is a square, a hexagon, or an octagon.
 8. The implantable device of claim 7, wherein a magnetic pole of each segment is normal to the face of the polygon.
 9. The implantable device of claim 6, wherein each magnetic segment comprises first and second mitered ends, and the first mitered end of each magnetic segment contacts the second mitered end of an adjacent magnet segment after the device has self-assembled into a polygon.
 10. The implantable device of claim 1, further comprising an attachment point.
 11. The implantable device of claim 10, wherein the attachment point comprises a suture.
 12. An implantable device comprising a plurality of individual and separate magnetic segments coupled together with an exterior coupling covering exterior portions of the plurality of magnetic segments, the exterior coupling comprises a deformable material configured to return to a default shape from one or more deformed shapes, wherein, when in the default shape, the exterior coupling is adapted to position and maintain alignment of the plurality of magnetic segments relative to one another to thereby direct the plurality of magnetic segments to self-assemble into a geometric shape based, at least in part, on magnetic attractive forces between adjacent magnetic segments.
 13. The implantable device of claim 12, wherein the device comprises four or more magnetic segments and the device self-assembles into a polygon.
 14. The implantable device of claim 13, wherein the polygon is a square, a hexagon, or an octagon.
 15. The implantable device of claim 13, wherein a magnetic pole of each segment is normal to the face of the polygon.
 16. An implantable device comprising: a plurality of magnetic segments; and an exterior guiding member coupled to at least two magnetic segments and covering exterior portions of the magnetic segments, wherein the exterior guiding member comprises a deformable material configured to return to a default shape from one or more deformed shapes, wherein, when in the default shape, the exterior guiding member is adapted to position and maintain alignment of the plurality of magnetic segments relative to one another to thereby direct the plurality of magnetic segments to reconfigure from a low-profile delivery configuration to a deployed configuration based, at least in part, on magnetic attractive forces between adjacent magnetic segments.
 17. The implantable device of claim 16, wherein the delivery configuration is substantially linear and the deployed configuration is a polygon.
 18. The implantable device of claim 17, wherein the polygon is a square, a hexagon, or an octagon.
 19. The implantable device of claim 17, wherein a magnetic pole of each segment is normal to the face of the polygon.
 20. The implantable device of claim 16, wherein the device comprises four or more magnetic segments. 